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  • Samba4 [homes] share

    - by SambaDrivesMeCrazy
    I am having issues with the [homes] share. OS is Ubuntu 12.04. I've installed samba 4.0.3, bind9 dlz, ntp, winbind, everything but pam modules, and did all the tests from https://wiki.samba.org/index.php/Samba_AD_DC_HOWTO. Running getent passwd and getent user work just fine. Creating a simple share works just fine too. I can manage the users, GPOs, and DNS from the windows mmc snap-ins. I can join winxp,7,8 to the domain and log on perfectly. I can change my passwords from windows, etc..etc.. I could say that everything is fine and be happy :) buuuut, no, home directories do not work. Searching in here, and on our good friend google I gathered that a simple [homes] read only = no path = /storage-server/users/ and mapping the user's home folder in dsa.msc to \\server-001\username or \\server-001\homes should get me a home share I could map for my user homedir. But the snap-in give me an error saying that it cannot create the home folder because the network name has not been found (rough translation from portuguese). also, running root@server-001:/storage-server/users# smbclient //server-001/test -Utest%'12345678' -c 'ls' Domain=[MYDOMAIN] OS=[Unix] Server=[Samba 4.0.3] tree connect failed: NT_STATUS_BAD_NETWORK_NAME Server name is alright, if I go for a simple share on the same server it opens just fine. If I map the user homedir to this simple share it works. What I want is that I dont have to go and manually make a new folder on linux everytime I create a new user on windows. It looks like permissions but I cant find any documentation on this (yes I've tried the manpages, but its hard to tell with so many options on man smb.conf alone). My smb.conf right now looks like this (pretty simple I know) # Global parameters [global] workgroup = MYDOMAIN realm = MYDOMAIN.LAN netbios name = SERVER-001 server role = active directory domain controller server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc, drepl, winbind, ntp_signd, kcc, dnsupdate [netlogon] path = /usr/local/samba/var/locks/sysvol/mydomain.lan/scripts read only = No [sysvol] path = /usr/local/samba/var/locks/sysvol read only = No [homes] read only = no path = /storage-server/users Folder permissions /storage-server drwxr-xr-x 6 root root 4096 Fev 15 15:17 storage-server /storage-server/users drwxrwxrwx 6 root root 4096 Fev 18 17:05 users/ Yes, I was desperate enough to set 777 on the users folder... not proud of it. Any pointers in the right direction would be very welcome. Edited to include: root@server-001:/# wbinfo --user-info=test MYDOMAIN\test:*:3000045:100:test:/home/MYDOMAIN/test:/bin/false root@server-001:/# wbinfo -n test S-1-5-21-1957592451-3401938807-633234758-1128 SID_USER (1) root@server-001:/# id test uid=3000045(MYDOMAIN\test) gid=100(users) grupos=100(users) root@server-001:/# wbinfo -U 3000045 S-1-5-21-1957592451-3401938807-633234758-1128 root@server-001:/# Edit 2: getent passwd | grep test MYDOMAIN\test:*:3000045:100:test:/home/MYDOMAIN/test:/bin/false I have no idea how to change that home folder to /storage-server/users/test so I just went and ln -s /storage-server/users /home/MYDOMAIN just in case. still, no changes, same errors. Edit 3 On log.smbd I get the following error when trying to set the test user home folder to \server-001\test [2013/02/20 14:22:08.446658, 2] ../source3/smbd/service.c:418(create_connection_session_info) user 'MYDOMAIN\Administrator' (from session setup) not permitted to access this share (test)

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  • reiserfsck on lvm

    - by DaDaDom
    It seems like my filesystem got corrupted somehow during the last reboot of my server. I can't fsck some logical volumes anymore. The setup: root@rescue ~ # cat /mnt/rescue/etc/fstab proc /proc proc defaults 0 0 /dev/md0 /boot ext3 defaults 0 2 /dev/md1 / ext3 defaults,errors=remount-ro 0 1 /dev/systemlvm/home /home reiserfs defaults 0 0 /dev/systemlvm/usr /usr reiserfs defaults 0 0 /dev/systemlvm/var /var reiserfs defaults 0 0 /dev/systemlvm/tmp /tmp reiserfs noexec,nosuid 0 2 /dev/sda5 none swap defaults,pri=1 0 0 /dev/sdb5 none swap defaults,pri=1 0 0 [UPDATE] First question: what "part" should I check for bad blocks? The logical volume, the underlying /dev/md or the /dev/sdx below that? Is doing what I am doing the right way to go? [/UPDATE] The errormessage when checking /dev/systemlvm/usr: root@rescue ~ # reiserfsck /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will read-only check consistency of the filesystem on /dev/systemlvm/usr Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes ########### reiserfsck --check started at Wed Feb 3 07:10:55 2010 ########### Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed Checking internal tree.. Bad root block 0. (--rebuild-tree did not complete) Aborted Well so far, let's try --rebuild-tree: root@rescue ~ # reiserfsck --rebuild-tree /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will rebuild the filesystem (/dev/systemlvm/usr) tree Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed ########### reiserfsck --rebuild-tree started at Wed Feb 3 07:12:27 2010 ########### Pass 0: ####### Pass 0 ####### Loading on-disk bitmap .. ok, 269716 blocks marked used Skipping 8250 blocks (super block, journal, bitmaps) 261466 blocks will be read 0%....20%....40%....60%....80%....100% left 0, 11368 /sec 52919 directory entries were hashed with "r5" hash. "r5" hash is selected Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13086 Objectids found 53697 Pass 1 (will try to insert 13086 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0% left 12675, 0 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. mark_block_used: (39508) used already Aborted Bad. But let's do it again as mentioned: [...] Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13085 Objectids found 54305 Pass 1 (will try to insert 13085 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0%... left 12127, 958 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. build_the_tree: Nothing but leaves are expected. Block 196736 - internal Aborted Same happens every time, only the actual error message changes. Sometimes I get mark_block_used: (somenumber) used already, other times the block number changes. Seems like something is REALLY broken. Are there any chances I can somehow get the partitions to work again? It's a server to which I don't have physical access directly (hosted server). Thanks in advance!

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  • How to setup linux permissions the WWW folder?

    - by Xeoncross
    Updated Summery The /var/www directory is owned by root:root which means that no one can use it and it's entirely useless. Since we all want a web server that actually works (and no-one should be logging in as "root"), then we need to fix this. Only two entities need access. PHP/Perl/Ruby/Python all need access to the folders and files since they create many of them (i.e. /uploads/). These scripting languages should be running under nginx or apache (or even some other thing like FastCGI for PHP). The developers How do they get access? I know that someone, somewhere has done this before. With however-many billions of websites out there you would think that there would be more information on this topic. I know that 777 is full read/write/execute permission for owner/group/other. So this doesn't seem to be needed as it leaves random users full permissions. What permissions are need to be used on /var/www so that... Source control like git or svn Users in a group like "websites" (or even added to "www-data") Servers like apache or lighthttpd And PHP/Perl/Ruby can all read, create, and run files (and directories) there? If I'm correct, Ruby and PHP scripts are not "executed" directly - but passed to an interpreter. So there is no need for execute permission on files in /var/www...? Therefore, it seems like the correct permission would be chmod -R 1660 which would make all files shareable by these four entities all files non-executable by mistake block everyone else from the directory entirely set the permission mode to "sticky" for all future files Is this correct? Update: I just realized that files and directories might need different permissions - I was talking about files above so i'm not sure what the directory permissions would need to be. Update 2: The folder structure of /var/www changes drastically as one of the four entities above are always adding (and sometimes removing) folders and sub folders many levels deep. They also create and remove files that the other 3 entities might need read/write access to. Therefore, the permissions need to do the four things above for both files and directories. Since non of them should need execute permission (see question about ruby/php above) I would assume that rw-rw-r-- permission would be all that is needed and completely safe since these four entities are run by trusted personal (see #2) and all other users on the system only have read access. Update 3: This is for personal development machines and private company servers. No random "web customers" like a shared host. Update 4: This article by slicehost seems to be the best at explaining what is needed to setup permissions for your www folder. However, I'm not sure what user or group apache/nginx with PHP OR svn/git run as and how to change them. Update 5: I have (I think) finally found a way to get this all to work (answer below). However, I don't know if this is the correct and SECURE way to do this. Therefore I have started a bounty. The person that has the best method of securing and managing the www directory wins.

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  • Wear and tear on server hard drive from filesystem polling by PHP script

    - by jackie
    So I'm working on a discussion platform, and various clients will visit http://host/thread.php, which will render the discussion thread to date in addition to a form to submit a new post. When a new post is submitted, I would like all of the other clients with browser windows open to have it appear in near-real-time. One of the constraints of my script is that it may not use a DBMS and it must stay in the filesystem. Additionally, I can't use any PECL/PEAR extensions like inotify or anything like that for IPC. The flow will look like this: Client A requests thread.php and the thread is so far empty, but nonetheless it opens a Server-Side Event at eventPusher.php. Client B does the same. Client A fills out a post in the form and and submits (POSTs) it to subHandler.php. ??? (subHandler stores the new submission into the main thread storefile which gets read from when a fresh, new client requests thread.php, in addition to somehow signalling to the continually-running eventPusher event-source that a new comment was posted and that it should echo the event-json to the client. How, exactly, it will send this signal I'm yet unsure of, but there are a few options that I've thought of -- this is the crux of the question, so see below for more clarification) eventPusher.php happily pushes the new event to the client and it shows up soon after it was originally submitted on all clients who have the page open's screens. Now for the #4 missing-link mystery-step, I see a few problems. I mean, either way, eventPusher is gonna be doing a while loop of some sort -- it's gonna be polling something, I think that much is clear. (If that's a bad assumption please do let me know.) Now, the simplest way would be subHandler gets invoked on the form submission, writes it to the main store in addition to newComments.xml, then exits without doing anything else. Then eventPusher checks in newComments.xml every X seconds (by the way, what would be a reasonable time interval here?) and if it finds something then it emits an event to the client. Now, my fear with this is that the server's hard drive will have to constantly start spinning up. Maybe this isn't the case, perhaps it would just get cached in RAM and the linux kernel would take care of this transparently such that filesystem access doesn't actually engage the device because the kernel knows that that particular file hasn't changed since last read. * idea #2: I have no idea how to go about this, but perhaps there is a variable scope that gets stored in general RAM on the system which can be read by any process. Like if we mega-exported a bash variable so that $new_post is normally false but it gets toggled to true by subHandler, and then back to flase once it's pushed to the client. I doubt there's such a variable scope in PHP directly, but I struggle with the concept of variable scope, I just can't seem to understand it no matter what I read on it. * idea #3: eventPusher queries ps in its whileloop for another instance of itself. If there's not another eventPusher active then it's highly unlikely that new comments will be getting submitted. It's okay if this only works =90% of the time, it doesn't need to be completely foolproof. * idea #4: eventPusher queries DMESG to see if that file's been written to recently. So to sum everything up, I need to have inter-php-script-communication in near-real-time that will work on a standard mod_php shared hosting setup without any elevated privileges, PHP addon modules, or other system adjustments that can't be done from the PHP script itself at runtime. With*out* spinning up the drive more than a few times. No SQL servers either. Apologies if my english isn't the best, I'm still trying to improve on it.

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  • stunnel crashing

    - by Jay
    I'm trying to use stunnel to secure a legacy application's communications. I can't seem to get it setup and working. Can anyone provide any hints where I'm going wrong? Here's what I'm trying to accomplish: A windows service on a client machine connects to a server on port 7000 using TCP. I'd like to encrypt the communication between client and server. Here's what I've tried: Created a new server that accepts ssl connections on port 7443. Got a certificate for the server and installed it. That seems to work with my test setup. Installed stunnel on my windows machine (version 7.43 from the distribution archive file). Installed libssl32.dll and libeay32.dll in the same directory as stunnel.exe ( from the openssl-0.9.8h-1 binary distribution). Installed it as a service using "stunnel -install" Configured stunnel as follows: debug=7 output=C:\p4\internal\Utility\Proxy\proxy.log service=Proxy taskbar=no [exchange] accept=7000 client=yes connect=proxy.blah.com:7443 I changed my hosts file to trick the old application into connecting through stunnel: server.blah.com 127.0.0.1 # when client looks up server it goes to stunnel proxy.blah.com IP-address-of-server.blah.com # stunnel connects to new server "server.blah.com" now resolves to the machine it's running on (i.e. stunnel). "proxy.blah.com" goes to the real server. stunnel should connect to the server. I start the stunnel service and try to connect. It looks like it's working but the stunnel service just shuts down with no message. 2010.04.19 13:16:21 LOG5[4924:3716]: stunnel 4.33 on x86-pc-mingw32-gnu with OpenSSL 0.9.8h 28 May 2008 2010.04.19 13:16:21 LOG5[4924:3716]: Threading:WIN32 SSL:ENGINE Sockets:SELECT,IPv6 2010.04.19 13:16:49 LOG5[4924:3748]: Service exchange accepted connection from 127.0.0.1:4134 2010.04.19 13:16:49 LOG6[4924:3748]: connect_blocking: connecting x.80.60.32:7443 2010.04.19 13:16:49 LOG5[4924:3748]: connect_blocking: connected x.80.60.32:7443 2010.04.19 13:16:49 LOG5[4924:3748]: Service exchange connected remote server from x.253.120.19:4135 2010.04.19 13:20:24 LOG5[3668:3856]: Reading configuration from file stunnel.conf 2010.04.19 13:20:24 LOG7[3668:3856]: Snagged 64 random bytes from C:/.rnd 2010.04.19 13:20:24 LOG7[3668:3856]: Wrote 1024 new random bytes to C:/.rnd 2010.04.19 13:20:24 LOG7[3668:3856]: RAND_status claims sufficient entropy for the PRNG 2010.04.19 13:20:24 LOG7[3668:3856]: PRNG seeded successfully 2010.04.19 13:20:24 LOG7[3668:3856]: SSL context initialized for service exchange 2010.04.19 13:20:24 LOG5[3668:3856]: Configuration successful 2010.04.19 13:20:24 LOG5[3668:3856]: No limit detected for the number of clients 2010.04.19 13:20:24 LOG7[3668:3856]: FD=312 in non-blocking mode 2010.04.19 13:20:24 LOG7[3668:3856]: Option SO_REUSEADDR set on accept socket 2010.04.19 13:20:24 LOG7[3668:3856]: Service exchange bound to 0.0.0.0:7000 2010.04.19 13:20:24 LOG7[3668:3856]: Service exchange opened FD=312 2010.04.19 13:20:24 LOG5[3668:3856]: stunnel 4.33 on x86-pc-mingw32-gnu with OpenSSL 0.9.8h 28 May 2008 2010.04.19 13:20:24 LOG5[3668:3856]: Threading:WIN32 SSL:ENGINE Sockets:SELECT,IPv6 2010.04.19 13:21:02 LOG7[3668:4556]: Service exchange accepted FD=372 from 127.0.0.1:4156 2010.04.19 13:21:02 LOG7[3668:4556]: Creating a new thread 2010.04.19 13:21:02 LOG7[3668:4556]: New thread created 2010.04.19 13:21:02 LOG7[3668:3756]: Service exchange started 2010.04.19 13:21:02 LOG7[3668:3756]: FD=372 in non-blocking mode 2010.04.19 13:21:02 LOG5[3668:3756]: Service exchange accepted connection from 127.0.0.1:4156 2010.04.19 13:21:02 LOG7[3668:3756]: FD=396 in non-blocking mode 2010.04.19 13:21:02 LOG6[3668:3756]: connect_blocking: connecting x.80.60.32:7443 2010.04.19 13:21:02 LOG7[3668:3756]: connect_blocking: s_poll_wait x.80.60.32:7443: waiting 10 seconds 2010.04.19 13:21:02 LOG5[3668:3756]: connect_blocking: connected x.80.60.32:7443 2010.04.19 13:21:02 LOG5[3668:3756]: Service exchange connected remote server from x.253.120.19:4157 2010.04.19 13:21:02 LOG7[3668:3756]: Remote FD=396 initialized 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): before/connect initialization 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 write client hello A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 read server hello A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 read server certificate A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 read server done A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 write client key exchange A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 write change cipher spec A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 write finished A 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 flush data 2010.04.19 13:21:02 LOG7[3668:3756]: SSL state (connect): SSLv3 read finished A The client thinks the connection is closed: No connection could be made because the target machine actively refused it 127.0.0.1:7000 at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) at System.Net.Sockets.Socket.Connect(EndPoint remoteEP) at Service.ConnUtility.Connect() Any suggestions?

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  • Cast exception when trying to create new Task Schedueler task.

    - by seaneshbaugh
    I'm attempting to create a new task in the Windows Task Scheduler in C#. What I've got so far is pretty much a copy and paste of http://bartdesmet.net/blogs/bart/archive/2008/02/23/calling-the-task-scheduler-in-windows-vista-and-windows-server-2008-from-managed-code.aspx Everything compiles just fine but come run time I get the following exception: Unable to cast COM object of type 'System.__ComObject' to interface type 'TaskScheduler.ITimeTrigger'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{B45747E0-EBA7-4276-9F29-85C5BB300006}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)). Here's all the code so you can see what I'm doing here without following the above link. TaskSchedulerClass Scheduler = new TaskSchedulerClass(); Scheduler.Connect(null, null, null, null); ITaskDefinition Task = Scheduler.NewTask(0); Task.RegistrationInfo.Author = "Test Task"; Task.RegistrationInfo.Description = "Just testing this out."; ITimeTrigger Trigger = (ITimeTrigger)Task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY); Trigger.Id = "TestTrigger"; Trigger.StartBoundary = "2010-05-12T06:15:00"; IShowMessageAction Action = (IShowMessageAction)Task.Actions.Create(_TASK_ACTION_TYPE.TASK_ACTION_SHOW_MESSAGE); Action.Id = "TestAction"; Action.Title = "Test Task"; Action.MessageBody = "This is a test."; ITaskFolder Root = Scheduler.GetFolder("\\"); IRegisteredTask RegisteredTask = Root.RegisterTaskDefinition("Background Backup", Task, (int)_TASK_CREATION.TASK_CREATE_OR_UPDATE, null, null, _TASK_LOGON_TYPE.TASK_LOGON_INTERACTIVE_TOKEN, ""); The line that is throwing the exception is this one ITimeTrigger Trigger = (ITimeTrigger)Task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY); The exception message kinda makes sense to me, but I'm afraid I don't know enough about COM to really know where to begin with this. Also, I should add that I'm using VS 2010 and I had to set the project to either be for x86 or x64 CPU's instead of the usual "Any CPU" because it kept giving me a BadImageFormatException. I doubt that's related to my current problem, but just in case I thought I might as well mention it.

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  • Java performance problem with LinkedBlockingQueue

    - by lofthouses
    Hello, this is my first post on stackoverflow...i hope someone can help me i have a big performance regression with Java 6 LinkedBlockingQueue. In the first thread i generate some objects which i push in to the queue In the second thread i pull these objects out. The performance regression occurs when the take() method of the LinkedBlockingQueue is called frequently. I monitored the whole program and the take() method claimed the most time overall. And the throughput goes from ~58Mb/s to 0.9Mb/s... the queue pop and take methods ar called with a static method from this class public class C_myMessageQueue { private static final LinkedBlockingQueue<C_myMessageObject> x_queue = new LinkedBlockingQueue<C_myMessageObject>( 50000 ); /** * @param message * @throws InterruptedException * @throws NullPointerException */ public static void addMyMessage( C_myMessageObject message ) throws InterruptedException, NullPointerException { x_queue.put( message ); } /** * @return Die erste message der MesseageQueue * @throws InterruptedException */ public static C_myMessageObject getMyMessage() throws InterruptedException { return x_queue.take(); } } how can i tune the take() method to accomplish at least 25Mb/s, or is there a other class i can use which will block when the "queue" is full or empty. kind regards Bart P.S.: sorry for my bad english, i'm from germany ;)

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  • EF 4.0 : Save Changes Retry Logic

    - by BGR
    Hi, I would like to implement an application wide retry system for all entity SaveChanges method calls. Technologies: Entity framework 4.0 .Net 4.0 namespace Sample.Data.Store.Entities { public partial class StoreDB { public override int SaveChanges(System.Data.Objects.SaveOptions options) { for (Int32 attempt = 1; ; ) { try { return base.SaveChanges(options); } catch (SqlException sqlException) { // Increment Trys attempt++; // Find Maximum Trys Int32 maxRetryCount = 5; // Throw Error if we have reach the maximum number of retries if (attempt == maxRetryCount) throw; // Determine if we should retry or abort. if (!RetryLitmus(sqlException)) throw; else Thread.Sleep(ConnectionRetryWaitSeconds(attempt)); } } } static Int32 ConnectionRetryWaitSeconds(Int32 attempt) { Int32 connectionRetryWaitSeconds = 2000; // Backoff Throttling connectionRetryWaitSeconds = connectionRetryWaitSeconds * (Int32)Math.Pow(2, attempt); return (connectionRetryWaitSeconds); } /// <summary> /// Determine from the exception if the execution /// of the connection should Be attempted again /// </summary> /// <param name="exception">Generic Exception</param> /// <returns>True if a a retry is needed, false if not</returns> static Boolean RetryLitmus(SqlException sqlException) { switch (sqlException.Number) { // The service has encountered an error // processing your request. Please try again. // Error code %d. case 40197: // The service is currently busy. Retry // the request after 10 seconds. Code: %d. case 40501: //A transport-level error has occurred when // receiving results from the server. (provider: // TCP Provider, error: 0 - An established connection // was aborted by the software in your host machine.) case 10053: return (true); } return (false); } } } The problem: How can I run the StoreDB.SaveChanges to retry on a new DB context after an error occured? Something simular to Detach/Attach might come in handy. Thanks in advance! Bart

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  • openvpn WARNING: No server certificate verification method has been enabled

    - by tmedtcom
    I tried to install openvpn on debian squeez (server) and connect from my fedora 17 as (client). Here is my configuration: server configuration ###cat server.conf # Serveur TCP ** proto tcp** port 1194 dev tun # Cles et certificats ca /etc/openvpn/easy-rsa/keys/ca.crt cert /etc/openvpn/easy-rsa/keys/server.crt key /etc/openvpn/easy-rsa/keys/server.key dh /etc/openvpn/easy-rsa/keys/dh1024.pem # Reseau #Adresse virtuel du reseau vpn server 192.170.70.0 255.255.255.0 #Cette ligne ajoute sur le client la route du reseau vers le serveur push "route 192.168.1.0 255.255.255.0" #Creer une route du server vers l'interface tun. #route 192.170.70.0 255.255.255.0 # Securite keepalive 10 120 #type d'encryptage des données **cipher AES-128-CBC** #activation de la compression comp-lzo #nombre maximum de clients autorisés max-clients 10 #pas d'utilisateur et groupe particuliers pour l'utilisation du VPN user nobody group nogroup #pour rendre la connexion persistante persist-key persist-tun #Log d'etat d'OpenVPN status /var/log/openvpn-status.log #logs openvpnlog /var/log/openvpn.log log-append /var/log/openvpn.log #niveau de verbosité verb 5 ###cat client.conf # Client client dev tun [COLOR="Red"]proto tcp-client[/COLOR] remote <my server wan IP> 1194 resolv-retry infinite **cipher AES-128-CBC** # Cles ca ca.crt cert client.crt key client.key # Securite nobind persist-key persist-tun comp-lzo verb 3 Message from the host client (fedora 17) in the log file / var / log / messages: Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> Starting VPN service 'openvpn'... Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' started (org.freedesktop.NetworkManager.openvpn), PID 7470 Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' appeared; activating connections Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN plugin state changed: starting (3) Dec 6 21:56:01 GlobalTIC NetworkManager[691]: <info> VPN connection 'Connexion VPN 1' (Connect) reply received. Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: OpenVPN 2.2.2 x86_64-redhat-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [eurephia] built on Sep 5 2012 Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"][U][B] WARNING: No server certificate verification method has been enabled.[/B][/U][/COLOR] See http://openvpn.net/howto.html#mitm for more info. Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: NOTE: the current --script-security setting may allow this configuration to call user-defined scripts Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"] WARNING: file '/home/login/client/client.key' is group or others accessible[/COLOR] Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link local: [undef] Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link remote: [COLOR="Red"]<my server wan IP>[/COLOR]:1194 Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4 [ECONNREFUSED]: Connection refused (code=111)[/COLOR] Dec 6 21:56:03 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4[/COLOR] [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:07 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:15 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:31 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:41 GlobalTIC NetworkManager[691]: <warn> VPN connection 'Connexion VPN 1' (IP Conf[/CODE] ifconfig on server host(debian): ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:16:21:ac inet addr:192.168.1.6 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fe16:21ac/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:9059 errors:0 dropped:0 overruns:0 frame:0 TX packets:5660 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:919427 (897.8 KiB) TX bytes:1273891 (1.2 MiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:192.170.70.1 P-t-P:192.170.70.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) ifconfig on the client host (fedora 17) as0t0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.0.1 netmask 255.255.252.0 destination 5.5.0.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t1: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.4.1 netmask 255.255.252.0 destination 5.5.4.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t2: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.8.1 netmask 255.255.252.0 destination 5.5.8.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t3: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.12.1 netmask 255.255.252.0 destination 5.5.12.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 **p255p1**: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.2 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::21d:baff:fe20:b7e6 prefixlen 64 scopeid 0x20<link> ether 00:1d:ba:20:b7:e6 txqueuelen 1000 (Ethernet) RX packets 4842070 bytes 3579798184 (3.3 GiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 3996158 bytes 2436442882 (2.2 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 16 p255p1 is label for eth0 interface and on the server : root@hoteserver:/etc/openvpn# tree . +-- client ¦** +-- ca.crt ¦** +-- client.conf ¦** +-- client.crt ¦** +-- client.csr ¦** +-- client.key ¦** +-- client.ovpn ¦* ¦** +-- easy-rsa ¦** +-- build-ca ¦** +-- build-dh ¦** +-- build-inter ¦** +-- build-key ¦** +-- build-key-pass ¦** +-- build-key-pkcs12 ¦** +-- build-key-server ¦** +-- build-req ¦** +-- build-req-pass ¦** +-- clean-all ¦** +-- inherit-inter ¦** +-- keys ¦** ¦** +-- 01.pem ¦** ¦** +-- 02.pem ¦** ¦** +-- ca.crt ¦** ¦** +-- ca.key ¦** ¦** +-- client.crt ¦** ¦** +-- client.csr ¦** ¦** +-- client.key ¦** ¦** +-- dh1024.pem ¦** ¦** +-- index.txt ¦** ¦** +-- index.txt.attr ¦** ¦** +-- index.txt.attr.old ¦** ¦** +-- index.txt.old ¦** ¦** +-- serial ¦** ¦** +-- serial.old ¦** ¦** +-- server.crt ¦** ¦** +-- server.csr ¦** ¦** +-- server.key ¦** +-- list-crl ¦** +-- Makefile ¦** +-- openssl-0.9.6.cnf.gz ¦** +-- openssl.cnf ¦** +-- pkitool ¦** +-- README.gz ¦** +-- revoke-full ¦** +-- sign-req ¦** +-- vars ¦** +-- whichopensslcnf +-- openvpn.log +-- openvpn-status.log +-- server.conf +-- update-resolv-conf on the client: [login@hoteclient openvpn]$ tree . |-- easy-rsa | |-- 1.0 | | |-- build-ca | | |-- build-dh | | |-- build-inter | | |-- build-key | | |-- build-key-pass | | |-- build-key-pkcs12 | | |-- build-key-server | | |-- build-req | | |-- build-req-pass | | |-- clean-all | | |-- list-crl | | |-- make-crl | | |-- openssl.cnf | | |-- README | | |-- revoke-crt | | |-- revoke-full | | |-- sign-req | | `-- vars | `-- 2.0 | |-- build-ca | |-- build-dh | |-- build-inter | |-- build-key | |-- build-key-pass | |-- build-key-pkcs12 | |-- build-key-server | |-- build-req | |-- build-req-pass | |-- clean-all | |-- inherit-inter | |-- keys [error opening dir] | |-- list-crl | |-- Makefile | |-- openssl-0.9.6.cnf | |-- openssl-0.9.8.cnf | |-- openssl-1.0.0.cnf | |-- pkitool | |-- README | |-- revoke-full | |-- sign-req | |-- vars | `-- whichopensslcnf |-- keys -> ./easy-rsa/2.0/keys/ `-- server.conf the problem source is cipher AES-128-CBC ,proto tcp-client or UDP or the interface p255p1 on fedora17 or file authentification ta.key is not found ????

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  • The Complete List of iPad Tips, Tricks, and Tutorials

    - by Ross
    The Apple iPad is the latest new toy, and we’ve put together a comprehensive list of every tip, trick, and tutorial that we could find to help you get the most out of it—and we’re even giving one away to one lucky reader. So read on! Note: We’ll be keeping this page updated as we find more great articles, so you should bookmark this page for future reference. Want Your Own iPad? How-To Geek is Giving One Away! All you have to do to enter is become a fan of our Facebook page, and we’ll pick a random fan to win the prize. Win an iPad on the How-To Geek Facebook Fan Page Disable the “clicking sound” on the iPad Keyboard Does the clicking sound when you tap the iPad keyboard bother you? Thankfully it’s easy to disable with a couple of taps. How to disable the “clicking sound” on your iPad’s keyboard Enable and add bookmarks to the Safari Bookmarks Bar on your iPad By default, Safari doesn’t display the Bookmarks Bar. This tip shows you how to change that. How to enable and add bookmarks to the Safari Bookmarks Bar on your iPad Clear the Cache, History and Cookies in Safari for the iPad You’re probably used to clearing this kind of data right from within the browser. Not so with Safari on the iPad – but here’s how you can. How to clear the cache, history and cookies in Safari for iPad How to add more Apps to your iPad Dock The iPad has four icons in its ‘dock’. Did you know it can hold 6? How to add more Apps to your iPad Dock Convert PDF files to ePub files to read on your iPad with iBooks ePub is the format that iBooks are in. So for those of you with large eBook collections in PDF, here’s how you convert them to read in iBooks. How to convert PDF files to ePub files to read on your iPad with iBooks How to force your iPad to restart Has an app caused your iPad to freeze up, and you can’t escape? This tip shows you how to force your iPad to restart. How to force your iPad to restart How to export Keynote for iPad presentations to your Mac or PC Exporting Keynote presentations from your iPad to your Mac or PC isn’t as straight forward as you might have expected. This tutorial shows you how. How to export Keynote for iPad presentations to your Mac or PC How to import presentations to Keynote on your iPad Having trouble getting your presentations onto your iPad? How to import presentations to Keynote on your iPad How to import documents to Pages on your iPad This guide shows you how to transfer documents (MS Word or Pages) from your Mac/PC to your iPad. How to import documents to Pages on your iPad How to insert photos in a Pages document using iPad and share it as a PDF Want to spice up that doc with a picture you just took? This tutorial will show you how – and how to export that document as a PDF. How to insert photos in a Pages document using iPad and share it as a PDF How to lock your iPad If you have kids or co-workers/friends who think it’s funny to mess with your iPad – lock it. How to lock your iPad How to remove the “Sent from my iPad” signature from outgoing email on your iPad Does everyone need to know you just sent that email from your iPad? Probably not. This guide shows you how to remove the “Sent from my iPad” signature and replace it with your own (or none). How to remove the “Sent from my iPad” signature from outgoing email on your iPad How To Sync Multiple Calendars to the iPad With Google Sync This tutorial will show you a workaround on how to sync multiple calendars on your iPad using Google Sync. How to Sync Multiple Calendars to the iPad With Google Sync How to determine the MAC address of your iPad If your network restricts connections via MAC address – this guide will show you how to determine what yours is. How to determine the MAC address of your iPad How to take a screenshot of your iPad Do you need to take a screenshot of your iPad? This quick tip shows you how to do just that. How to take a screenshot of your iPad How to delete apps from your iPod Touch, iPhone or iPad Anyone who had an iPod Touch or iPhone before they had an iPad won’t need this tutorial. But if you’re new to the experience, this one will help. How to delete apps from your iPod Touch, iPhone or iPad How to determine the iPad ECID on Windows and Mac iPadintosh shows us how to determine the iPad’s ECID code – something you’ll want to have come Jailbreak time. How to grab the iPad ECID in Windows or OS X iPad Apps: Twitter and social networking essentials Enggadget has you covered with reviews of the first slew of iPad specific Twitter and other social networking apps. iPad Apps: Twitter and social networking essentials What does your website look like on an iPad? iPad Peek is a web based tool that allows you to enter any given URL, and it will display that page the same way Safari on the iPad does. Great for web site owners who don’t have access to an iPad. iPadPeek Stream Music and Videos to your iPad Gizmodo reviews the iPad app StreamToMe, which allows you to stream media from your Mac to your iPad across your local network. Their feelings in a nutshell – worth the $3, but not perfect. Review: StreamToMe for the iPad Apple iPad : Change links in Google Reader to point to full HTML webpage How to change links in Safari for iPad so that Google Reader points to a full HTML webpage How to connect an iPad to your existing wireless keyboard This video will show you how to connect your iPad to a wireless keyboard if you’re having any problems – and from the sound of things, quite a few folks are. via TUAW How to get started with the iPad Mashable has a very entry-level guide that will help you set up your iPad for the first time. Mashable’s Guide to Setting up the iPad Essential iPad Apps Downloadsquad gives mini-reviews to 8 iPad apps that you should install as soon as you get your iPad. iPad App Buyers Guide: Essential Apps you should get on day one Videos: The Official iPad Guided Tours From none other than Apple! Great getting started videos for all the included iPad apps. The Official iPad Guided Tours The Official iPad Manual When you buy an iPad, you don’t get a manual. But that’s not to say there isn’t one. Apple provides a 150 guide for your iPad in PDF format. The Official iPad Manual (pdf) How to print from your iPad Sure, it’s actually just an App (PrintCentral – $9.99 USD), but as of right now, it’s the only way. PrintCentral How to make your own iPad Wallpaper A perfectly detailed tutorial on how to make your own wallpaper for your iPad. The author also provides a really nice sample wallpaper, published under the Attribution-Noncommercial 2.0 Generic license. How to make your own iPad Wallpaper Got any more tips? Share them in the comments, and we’ll update the post with the links, or just the tip itself. Similar Articles Productive Geek Tips Want an iPad? How-To Geek is Giving One Away!Why Wait? Amazing New Add-on Turns Your iPhone into an iPad! [Comic]Clear the Auto-Complete Email Address Cache in OutlookAsk the Readers: Share Your Tips for Defeating Viruses and MalwareStupid Geek Tricks: Tile or Cascade Multiple Windows in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition Penolo Lets You Share Sketches On Twitter Visit Woolyss.com for Old School Games, Music and Videos

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  • Developer’s Life – Attitude and Communication – They Can Cause Problems – Notes from the Field #027

    - by Pinal Dave
    [Note from Pinal]: This is a 27th episode of Notes from the Field series. The biggest challenge for anyone is to understand human nature. We human have so many things on our mind at any moment of time. There are cases when what we say is not what we mean and there are cases where what we mean we do not say. We do say and things as per our mood and our agenda in mind. Sometimes there are incidents when our attitude creates confusion in the communication and we end up creating a situation which is absolutely not warranted. In this episode of the Notes from the Field series database expert Mike Walsh explains a very crucial issue we face in our career, which is not technical but more to relate to human nature. Read on this may be the best blog post you might read in recent times. In this week’s note from the field, I’m taking a slight departure from technical knowledge and concepts explained. We’ll be back to it next week, I’m sure. Pinal wanted us to explain some of the issues we bump into and how we see some of our customers arrive at problem situations and how we have helped get them back on the right track. Often it is a technical problem we are officially solving – but in a lot of cases as a consultant, we are really helping fix some communication difficulties. This is a technical blog post and not an “advice column” in a newspaper – but the longer I am a consultant, the more years I add to my experience in technology the more I learn that the vast majority of the problems we encounter have “soft skills” included in the chain of causes for the issue we are helping overcome. This is not going to be exhaustive but I hope that sharing four pieces of advice inspired by real issues starts a process of searching for places where we can be the cause of these challenges and look at fixing them in ourselves. Or perhaps we can begin looking at resolving them in teams that we manage. I’ll share three statements that I’ve either heard, read or said and talk about some of the communication or attitude challenges highlighted by the statement. 1 – “But that’s the SAN Administrator’s responsibility…” I heard that early on in my consulting career when talking with a customer who had serious corruption and no good recent backups – potentially no good backups at all. The statement doesn’t have to be this one exactly, but the attitude here is an attitude of “my job stops here, and I don’t care about the intent or principle of why I’m here.” It’s also a situation of having the attitude that as long as there is someone else to blame, I’m fine…  You see in this case, the DBA had a suspicion that the backups were not being handled right.  They were the DBA and they knew that they had responsibility to ensure SQL backups were good to go – it’s a basic requirement of a production DBA. In my “As A DBA Where Do I start?!” presentation, I argue that is job #1 of a DBA. But in this case, the thought was that there was someone else to blame. Rather than create extra work and take on responsibility it was decided to just let it be another team’s responsibility. This failed the company, the company’s customers and no one won. As technologists – we should strive to go the extra mile. If there is a lack of clarity around roles and responsibilities and we know it – we should push to get it resolved. Especially as the DBAs who should act as the advocates of the data contained in the databases we are responsible for. 2 – “We’ve always done it this way, it’s never caused a problem before!” Complacency. I have to say that many failures I’ve been paid good money to help recover from would have not happened had it been for an attitude of complacency. If any thoughts like this have entered your mind about your situation you may be suffering from it. If, while reading this, you get this sinking feeling in your stomach about that one thing you know should be fixed but haven’t done it.. Why don’t you stop and go fix it then come back.. “We should have better backups, but we’re on a SAN so we should be fine really.” “Technically speaking that could happen, but what are the chances?” “We’ll just clean that up as a fast follow” ..and so on. In the age of tightening IT budgets, increased expectations of up time, availability and performance there is no room for complacency. Our customers and business units expect – no demand – the best. Complacency says “we will give you second best or hopefully good enough and we accept the risk and know this may hurt us later. Sometimes an organization will opt for “good enough” and I agree with the concept that at times the perfect can be the enemy of the good. But when we make those decisions in a vacuum and are not reporting them up and discussing them as an organization that is different. That is us unilaterally choosing to do something less than the best and purposefully playing a game of chance. 3 – “This device must accept interference from other devices but not create any” I’ve paraphrased this one – but it’s something the Federal Communications Commission – a federal agency in the United States that regulates electronic communication – requires of all manufacturers of any device that could cause or receive interference electronically. I blogged in depth about this here (http://www.straightpathsql.com/archives/2011/07/relationship-advice-from-the-fcc/) so I won’t go into much detail other than to say this… If we all operated more on the premise that we should do our best to not be the cause of conflict, and to be less easily offended and less upset when we perceive offense life would be easier in many areas! This doesn’t always cause the issues we are called in to help out. Not directly. But where we see it is in unhealthy relationships between the various technology teams at a client. We’ll see teams hoarding knowledge, not sharing well with others and almost working against other teams instead of working with them. If you trace these problems back far enough it often stems from someone or some group of people violating this principle from the FCC. To Sum It Up Technology problems are easy to solve. At Linchpin People we help many customers get past the toughest technological challenge – and at the end of the day it is really just a repeatable process of pattern based troubleshooting, logical thinking and starting at the beginning and carefully stepping through to the end. It’s easy at the end of the day. The tough part of what we do as consultants is the people skills. Being able to help get teams working together, being able to help teams take responsibility, to improve team to team communication? That is the difficult part, and we get to use the soft skills on every engagement. Work on professional development (http://professionaldevelopment.sqlpass.org/) and see continuing improvement here, not just with technology. I can teach just about anyone how to be an excellent DBA and performance tuner, but some of these soft skills are much more difficult to teach. If you want to get started with performance analytics and triage of virtualized SQL Servers with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • How to change Matlab program for solving equation with finite element method?

    - by DSblizzard
    I don't know is this question more related to mathematics or programming and I'm absolute newbie in Matlab. Program FEM_50 applies the finite element method to Laplace's equation -Uxx(x, y) - Uyy(x, y) = F(x, y) in Omega. How to change it to apply FEM to equation -Uxx(x, y) - Uyy(x, y) + U(x, y) = F(x, y)? At this page: http://sc.fsu.edu/~burkardt/m_src/fem_50/fem_50.html additional code files in case you need them. function fem_50 ( ) %% FEM_50 applies the finite element method to Laplace's equation. % % Discussion: % % FEM_50 is a set of MATLAB routines to apply the finite % element method to solving Laplace's equation in an arbitrary % region, using about 50 lines of MATLAB code. % % FEM_50 is partly a demonstration, to show how little it % takes to implement the finite element method (at least using % every possible MATLAB shortcut.) The user supplies datafiles % that specify the geometry of the region and its arrangement % into triangular and quadrilateral elements, and the location % and type of the boundary conditions, which can be any mixture % of Neumann and Dirichlet. % % The unknown state variable U(x,y) is assumed to satisfy % Laplace's equation: % -Uxx(x,y) - Uyy(x,y) = F(x,y) in Omega % with Dirichlet boundary conditions % U(x,y) = U_D(x,y) on Gamma_D % and Neumann boundary conditions on the outward normal derivative: % Un(x,y) = G(x,y) on Gamma_N % If Gamma designates the boundary of the region Omega, % then we presume that % Gamma = Gamma_D + Gamma_N % but the user is free to determine which boundary conditions to % apply. Note, however, that the problem will generally be singular % unless at least one Dirichlet boundary condition is specified. % % The code uses piecewise linear basis functions for triangular elements, % and piecewise isoparametric bilinear basis functions for quadrilateral % elements. % % The user is required to supply a number of data files and MATLAB % functions that specify the location of nodes, the grouping of nodes % into elements, the location and value of boundary conditions, and % the right hand side function in Laplace's equation. Note that the % fact that the geometry is completely up to the user means that % just about any two dimensional region can be handled, with arbitrary % shape, including holes and islands. % clear % % Read the nodal coordinate data file. % load coordinates.dat; % % Read the triangular element data file. % load elements3.dat; % % Read the quadrilateral element data file. % load elements4.dat; % % Read the Neumann boundary condition data file. % I THINK the purpose of the EVAL command is to create an empty NEUMANN array % if no Neumann file is found. % eval ( 'load neumann.dat;', 'neumann=[];' ); % % Read the Dirichlet boundary condition data file. % load dirichlet.dat; A = sparse ( size(coordinates,1), size(coordinates,1) ); b = sparse ( size(coordinates,1), 1 ); % % Assembly. % for j = 1 : size(elements3,1) A(elements3(j,:),elements3(j,:)) = A(elements3(j,:),elements3(j,:)) ... + stima3(coordinates(elements3(j,:),:)); end for j = 1 : size(elements4,1) A(elements4(j,:),elements4(j,:)) = A(elements4(j,:),elements4(j,:)) ... + stima4(coordinates(elements4(j,:),:)); end % % Volume Forces. % for j = 1 : size(elements3,1) b(elements3(j,:)) = b(elements3(j,:)) ... + det( [1,1,1; coordinates(elements3(j,:),:)'] ) * ... f(sum(coordinates(elements3(j,:),:))/3)/6; end for j = 1 : size(elements4,1) b(elements4(j,:)) = b(elements4(j,:)) ... + det([1,1,1; coordinates(elements4(j,1:3),:)'] ) * ... f(sum(coordinates(elements4(j,:),:))/4)/4; end % % Neumann conditions. % if ( ~isempty(neumann) ) for j = 1 : size(neumann,1) b(neumann(j,:)) = b(neumann(j,:)) + ... norm(coordinates(neumann(j,1),:) - coordinates(neumann(j,2),:)) * ... g(sum(coordinates(neumann(j,:),:))/2)/2; end end % % Determine which nodes are associated with Dirichlet conditions. % Assign the corresponding entries of U, and adjust the right hand side. % u = sparse ( size(coordinates,1), 1 ); BoundNodes = unique ( dirichlet ); u(BoundNodes) = u_d ( coordinates(BoundNodes,:) ); b = b - A * u; % % Compute the solution by solving A * U = B for the remaining unknown values of U. % FreeNodes = setdiff ( 1:size(coordinates,1), BoundNodes ); u(FreeNodes) = A(FreeNodes,FreeNodes) \ b(FreeNodes); % % Graphic representation. % show ( elements3, elements4, coordinates, full ( u ) ); return end

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  • SQL SERVER – Faster SQL Server Databases and Applications – Power and Control with SafePeak Caching Options

    - by Pinal Dave
    Update: This blog post is written based on the SafePeak, which is available for free download. Today, I’d like to examine more closely one of my preferred technologies for accelerating SQL Server databases, SafePeak. Safepeak’s software provides a variety of advanced data caching options, techniques and tools to accelerate the performance and scalability of SQL Server databases and applications. I’d like to look more closely at some of these options, as some of these capabilities could help you address lagging database and performance on your systems. To better understand the available options, it is best to start by understanding the difference between the usual “Basic Caching” vs. SafePeak’s “Dynamic Caching”. Basic Caching Basic Caching (or the stale and static cache) is an ability to put the results from a query into cache for a certain period of time. It is based on TTL, or Time-to-live, and is designed to stay in cache no matter what happens to the data. For example, although the actual data can be modified due to DML commands (update/insert/delete), the cache will still hold the same obsolete query data. Meaning that with the Basic Caching is really static / stale cache.  As you can tell, this approach has its limitations. Dynamic Caching Dynamic Caching (or the non-stale cache) is an ability to put the results from a query into cache while maintaining the cache transaction awareness looking for possible data modifications. The modifications can come as a result of: DML commands (update/insert/delete), indirect modifications due to triggers on other tables, executions of stored procedures with internal DML commands complex cases of stored procedures with multiple levels of internal stored procedures logic. When data modification commands arrive, the caching system identifies the related cache items and evicts them from cache immediately. In the dynamic caching option the TTL setting still exists, although its importance is reduced, since the main factor for cache invalidation (or cache eviction) become the actual data updates commands. Now that we have a basic understanding of the differences between “basic” and “dynamic” caching, let’s dive in deeper. SafePeak: A comprehensive and versatile caching platform SafePeak comes with a wide range of caching options. Some of SafePeak’s caching options are automated, while others require manual configuration. Together they provide a complete solution for IT and Data managers to reach excellent performance acceleration and application scalability for  a wide range of business cases and applications. Automated caching of SQL Queries: Fully/semi-automated caching of all “read” SQL queries, containing any types of data, including Blobs, XMLs, Texts as well as all other standard data types. SafePeak automatically analyzes the incoming queries, categorizes them into SQL Patterns, identifying directly and indirectly accessed tables, views, functions and stored procedures; Automated caching of Stored Procedures: Fully or semi-automated caching of all read” stored procedures, including procedures with complex sub-procedure logic as well as procedures with complex dynamic SQL code. All procedures are analyzed in advance by SafePeak’s  Metadata-Learning process, their SQL schemas are parsed – resulting with a full understanding of the underlying code, objects dependencies (tables, views, functions, sub-procedures) enabling automated or semi-automated (manually review and activate by a mouse-click) cache activation, with full understanding of the transaction logic for cache real-time invalidation; Transaction aware cache: Automated cache awareness for SQL transactions (SQL and in-procs); Dynamic SQL Caching: Procedures with dynamic SQL are pre-parsed, enabling easy cache configuration, eliminating SQL Server load for parsing time and delivering high response time value even in most complicated use-cases; Fully Automated Caching: SQL Patterns (including SQL queries and stored procedures) that are categorized by SafePeak as “read and deterministic” are automatically activated for caching; Semi-Automated Caching: SQL Patterns categorized as “Read and Non deterministic” are patterns of SQL queries and stored procedures that contain reference to non-deterministic functions, like getdate(). Such SQL Patterns are reviewed by the SafePeak administrator and in usually most of them are activated manually for caching (point and click activation); Fully Dynamic Caching: Automated detection of all dependent tables in each SQL Pattern, with automated real-time eviction of the relevant cache items in the event of “write” commands (a DML or a stored procedure) to one of relevant tables. A default setting; Semi Dynamic Caching: A manual cache configuration option enabling reducing the sensitivity of specific SQL Patterns to “write” commands to certain tables/views. An optimization technique relevant for cases when the query data is either known to be static (like archive order details), or when the application sensitivity to fresh data is not critical and can be stale for short period of time (gaining better performance and reduced load); Scheduled Cache Eviction: A manual cache configuration option enabling scheduling SQL Pattern cache eviction based on certain time(s) during a day. A very useful optimization technique when (for example) certain SQL Patterns can be cached but are time sensitive. Example: “select customers that today is their birthday”, an SQL with getdate() function, which can and should be cached, but the data stays relevant only until 00:00 (midnight); Parsing Exceptions Management: Stored procedures that were not fully parsed by SafePeak (due to too complex dynamic SQL or unfamiliar syntax), are signed as “Dynamic Objects” with highest transaction safety settings (such as: Full global cache eviction, DDL Check = lock cache and check for schema changes, and more). The SafePeak solution points the user to the Dynamic Objects that are important for cache effectiveness, provides easy configuration interface, allowing you to improve cache hits and reduce cache global evictions. Usually this is the first configuration in a deployment; Overriding Settings of Stored Procedures: Override the settings of stored procedures (or other object types) for cache optimization. For example, in case a stored procedure SP1 has an “insert” into table T1, it will not be allowed to be cached. However, it is possible that T1 is just a “logging or instrumentation” table left by developers. By overriding the settings a user can allow caching of the problematic stored procedure; Advanced Cache Warm-Up: Creating an XML-based list of queries and stored procedure (with lists of parameters) for periodically automated pre-fetching and caching. An advanced tool allowing you to handle more rare but very performance sensitive queries pre-fetch them into cache allowing high performance for users’ data access; Configuration Driven by Deep SQL Analytics: All SQL queries are continuously logged and analyzed, providing users with deep SQL Analytics and Performance Monitoring. Reduce troubleshooting from days to minutes with database objects and SQL Patterns heat-map. The performance driven configuration helps you to focus on the most important settings that bring you the highest performance gains. Use of SafePeak SQL Analytics allows continuous performance monitoring and analysis, easy identification of bottlenecks of both real-time and historical data; Cloud Ready: Available for instant deployment on Amazon Web Services (AWS). As you can see, there are many options to configure SafePeak’s SQL Server database and application acceleration caching technology to best fit a lot of situations. If you’re not familiar with their technology, they offer free-trial software you can download that comes with a free “help session” to help get you started. You can access the free trial here. Also, SafePeak is available to use on Amazon Cloud. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – Core Concepts – Elasticity, Scalability and ACID Properties – Exploring NuoDB an Elastically Scalable Database System

    - by pinaldave
    I have been recently exploring Elasticity and Scalability attributes of databases. You can see that in my earlier blog posts about NuoDB where I wanted to look at Elasticity and Scalability concepts. The concepts are very interesting, and intriguing as well. I have discussed these concepts with my friend Joyti M and together we have come up with this interesting read. The goal of this article is to answer following simple questions What is Elasticity? What is Scalability? How ACID properties vary from NOSQL Concepts? What are the prevailing problems in the current database system architectures? Why is NuoDB  an innovative and welcome change in database paradigm? Elasticity This word’s original form is used in many different ways and honestly it does do a decent job in holding things together over the years as a person grows and contracts. Within the tech world, and specifically related to software systems (database, application servers), it has come to mean a few things - allow stretching of resources without reaching the breaking point (on demand). What are resources in this context? Resources are the usual suspects – RAM/CPU/IO/Bandwidth in the form of a container (a process or bunch of processes combined as modules). When it is about increasing resources the simplest idea which comes to mind is the addition of another container. Another container means adding a brand new physical node. When it is about adding a new node there are two questions which comes to mind. 1) Can we add another node to our software system? 2) If yes, does adding new node cause downtime for the system? Let us assume we have added new node, let us see what the new needs of the system are when a new node is added. Balancing incoming requests to multiple nodes Synchronization of a shared state across multiple nodes Identification of “downstate” and resolution action to bring it to “upstate” Well, adding a new node has its advantages as well. Here are few of the positive points Throughput can increase nearly horizontally across the node throughout the system Response times of application will increase as in-between layer interactions will be improved Now, Let us put the above concepts in the perspective of a Database. When we mention the term “running out of resources” or “application is bound to resources” the resources can be CPU, Memory or Bandwidth. The regular approach to “gain scalability” in the database is to look around for bottlenecks and increase the bottlenecked resource. When we have memory as a bottleneck we look at the data buffers, locks, query plans or indexes. After a point even this is not enough as there needs to be an efficient way of managing such large workload on a “single machine” across memory and CPU bound (right kind of scheduling)  workload. We next move on to either read/write separation of the workload or functionality-based sharing so that we still have control of the individual. But this requires lots of planning and change in client systems in terms of knowing where to go/update/read and for reporting applications to “aggregate the data” in an intelligent way. What we ideally need is an intelligent layer which allows us to do these things without us getting into managing, monitoring and distributing the workload. Scalability In the context of database/applications, scalability means three main things Ability to handle normal loads without pressure E.g. X users at the Y utilization of resources (CPU, Memory, Bandwidth) on the Z kind of hardware (4 processor, 32 GB machine with 15000 RPM SATA drives and 1 GHz Network switch) with T throughput Ability to scale up to expected peak load which is greater than normal load with acceptable response times Ability to provide acceptable response times across the system E.g. Response time in S milliseconds (or agreed upon unit of measure) – 90% of the time The Issue – Need of Scale In normal cases one can plan for the load testing to test out normal, peak, and stress scenarios to ensure specific hardware meets the needs. With help from Hardware and Software partners and best practices, bottlenecks can be identified and requisite resources added to the system. Unfortunately this vertical scale is expensive and difficult to achieve and most of the operational people need the ability to scale horizontally. This helps in getting better throughput as there are physical limits in terms of adding resources (Memory, CPU, Bandwidth and Storage) indefinitely. Today we have different options to achieve scalability: Read & Write Separation The idea here is to do actual writes to one store and configure slaves receiving the latest data with acceptable delays. Slaves can be used for balancing out reads. We can also explore functional separation or sharing as well. We can separate data operations by a specific identifier (e.g. region, year, month) and consolidate it for reporting purposes. For functional separation the major disadvantage is when schema changes or workload pattern changes. As the requirement grows one still needs to deal with scale need in manual ways by providing an abstraction in the middle tier code. Using NOSQL solutions The idea is to flatten out the structures in general to keep all values which are retrieved together at the same store and provide flexible schema. The issue with the stores is that they are compromising on mostly consistency (no ACID guarantees) and one has to use NON-SQL dialect to work with the store. The other major issue is about education with NOSQL solutions. Would one really want to make these compromises on the ability to connect and retrieve in simple SQL manner and learn other skill sets? Or for that matter give up on ACID guarantee and start dealing with consistency issues? Hybrid Deployment – Mac, Linux, Cloud, and Windows One of the challenges today that we see across On-premise vs Cloud infrastructure is a difference in abilities. Take for example SQL Azure – it is wonderful in its concepts of throttling (as it is shared deployment) of resources and ability to scale using federation. However, the same abilities are not available on premise. This is not a mistake, mind you – but a compromise of the sweet spot of workloads, customer requirements and operational SLAs which can be supported by the team. In today’s world it is imperative that databases are available across operating systems – which are a commodity and used by developers of all hues. An Ideal Database Ability List A system which allows a linear scale of the system (increase in throughput with reasonable response time) with the addition of resources A system which does not compromise on the ACID guarantees and require developers to learn new paradigms A system which does not force fit a new way interacting with database by learning Non-SQL dialect A system which does not force fit its mechanisms for providing availability across its various modules. Well NuoDB is the first database which has all of the above abilities and much more. In future articles I will cover my hands-on experience with it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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  • How to get full control of umask/PAM/permissions?

    - by plua
    OUR SITUATION Several people from our company log in to a server and upload files. They all need to be able to upload and overwrite the same files. They have different usernames, but are all part of the same group. However, this is an internet server, so the "other" users should have (in general) just read-only access. So what I want to have is these standard permissions: files: 664 directories: 771 My goal is that all users do not need to worry about permissions. The server should be configured in such a way that these permissions apply to all files and directories, newly created, copied, or over-written. Only when we need some special permissions we'd manually change this. We upload files to the server by SFTP-ing in Nautilus, by mounting the server using sshfs and accessing it in Nautilus as if it were a local folder, and by SCP-ing in the command line. That basically covers our situation and what we aim to do. Now, I have read many things about the beautiful umask functionality. From what I understand umask (together with PAM) should allow me to do exactly what I want: set standard permissions for new files and directories. However, after many many hours of reading and trial-and-error, I still do not get this to work. I get many unexpected results. I really like to get a solid grasp of umask and have many question unanswered. I will post these questions below, together with my findings and an explanation of my trials that led to these questions. Given that many things appear to go wrong, I think that I am doing several things wrong. So therefore, there are many questions. NOTE: I am using Ubuntu 9.10 and therefore can not change the sshd_config to set the umask for the SFTP server. Installed SSH OpenSSH_5.1p1 Debian-6ubuntu2 < required OpenSSH 5.4p1. So here go the questions. 1. DO I NEED TO RESTART FOR PAM CHANGS TO TAKE EFFECT? Let's start with this. There were so many files involved and I was unable to figure out what does and what does not affect things, also because I did not know whether or not I have to restart the whole system for PAM changes to take effect. I did do so after not seeing the expected results, but is this really necessary? Or can I just log out from the server and log back in, and should new PAM policies be effective? Or is there some 'PAM' program to reload? 2. IS THERE ONE SINGLE FILE TO CHANGE THAT AFFECTS ALL USERS FOR ALL SESSIONS? So I ended up changing MANY files, as I read MANY different things. I ended up setting the umask in the following files: ~/.profile -> umask=0002 ~/.bashrc -> umask=0002 /etc/profile -> umask=0002 /etc/pam.d/common-session -> umask=0002 /etc/pam.d/sshd -> umask=0002 /etc/pam.d/login -> umask=0002 I want this change to apply to all users, so some sort of system-wide change would be best. Can it be achieved? 3. AFTER ALL, THIS UMASK THING, DOES IT WORK? So after changing umask to 0002 at every possible place, I run tests. ------------SCP----------- TEST 1: scp testfile (which has 777 permissions for testing purposes) server:/home/ testfile 100% 4 0.0KB/s 00:00 Let's check permissions: user@server:/home$ ls -l total 4 -rwx--x--x 1 user uploaders 4 2011-02-05 17:59 testfile (711) ---------SSH------------ TEST 2: ssh server user@server:/home$ touch anotherfile user@server:/home$ ls -l total 4 -rw-rw-r-- 1 user uploaders 0 2011-02-05 18:03 anotherfile (664) --------SFTP----------- Nautilus: sftp://server/home/ Copy and paste newfile from client to server (777 on client) TEST 3: user@server:/home$ ls -l total 4 -rwxrwxrwx 1 user uploaders 3 2011-02-05 18:05 newfile (777) Create a new file through Nautilus. Check file permissions in terminal: TEST 4: user@server:/home$ ls -l total 4 -rw------- 1 user uploaders 0 2011-02-05 18:06 newfile (600) I mean... WHAT just happened here?! We should get 644 every single time. Instead I get 711, 777, 600, and then once 644. And the 644 is only achieved when creating a new, blank file through SSH, which is the least probable scenario. So I am asking, does umask/pam work after all? 4. SO WHAT DOES IT MEAN TO UMASK SSHFS? Sometimes we mount a server locally, using sshfs. Very useful. But again, we have permissions issues. Here is how we mount: sshfs -o idmap=user -o umask=0113 user@server:/home/ /mnt NOTE: we use umask = 113 because apparently, sshfs starts from 777 instead of 666, so with 113 we get 664 which is the desired file permission. But what now happens is that we see all files and directories as if they are 664. We browse in Nautilus to /mnt and: Right click - New File (newfile) --- TEST 5 Right click - New Folder (newfolder) --- TEST 6 Copy and paste a 777 file from our local client --- TEST 7 So let's check on the command line: user@client:/mnt$ ls -l total 8 -rw-rw-r-- 1 user 1007 3 Feb 5 18:05 copyfile (664) -rw-rw-r-- 1 user 1007 0 Feb 5 18:15 newfile (664) drw-rw-r-- 1 user 1007 4096 Feb 5 18:15 newfolder (664) But hey, let's check this same folder on the server-side: user@server:/home$ ls -l total 8 -rwxrwxrwx 1 user uploaders 3 2011-02-05 18:05 copyfile (777) -rw------- 1 user uploaders 0 2011-02-05 18:15 newfile (600) drwx--x--x 2 user uploaders 4096 2011-02-05 18:15 newfolder (711) What?! The REAL file permissions are very different from what we see in Nautilus. So does this umask on sshfs just create a 'filter' that shows unreal file permissions? And I tried to open a file from another user but the same group that had real 600 permissions but 644 'fake' permissions, and I could still not read this, so what good is this filter?? 5. UMASK IS ALL ABOUT FILES. BUT WHAT ABOUT DIRECTORIES? From my tests I can see that the umask that is being applied also somehow influences the directory permissions. However, I want my files to be 664 (002) and my directories to be 771 (006). So is it possible to have a different umask for directories? 6. PERHAPS UMASK/PAM IS REALLY COOL, BUT UBUNTU IS JUST BUGGY? On the one hand, I have read topics of people that have had success with PAM/UMASK and Ubuntu. On the other hand, I have found many older and newer bugs regarding umask/PAM/fuse on Ubuntu: https://bugs.launchpad.net/ubuntu/+source/gdm/+bug/241198 https://bugs.launchpad.net/ubuntu/+source/fuse/+bug/239792 https://bugs.launchpad.net/ubuntu/+source/pam/+bug/253096 https://bugs.launchpad.net/ubuntu/+source/sudo/+bug/549172 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314796 So I do not know what to believe anymore. Should I just give up? Would ACL solve all my problems? Or do I have again problems using Ubuntu? One word of caution with backups using tar. Red Hat /Centos distributions support acls in the tar program but Ubuntu does not support acls when backing up. This means that all acls will be lost when you create a backup. I am very willing to upgrade to Ubuntu 10.04 if that would solve my problems too, but first I want to understand what is happening.

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  • Cost Comparison Hard Disk Drive to Solid State Drive on Price per Gigabyte - dispelling a myth!

    - by tonyrogerson
    It is often said that Hard Disk Drive storage is significantly cheaper per GiByte than Solid State Devices – this is wholly inaccurate within the database space. People need to look at the cost of the complete solution and not just a single component part in isolation to what is really required to meet the business requirement. Buying a single Hitachi Ultrastar 600GB 3.5” SAS 15Krpm hard disk drive will cost approximately £239.60 (http://scan.co.uk, 22nd March 2012) compared to an OCZ 600GB Z-Drive R4 CM84 PCIe costing £2,316.54 (http://scan.co.uk, 22nd March 2012); I’ve not included FusionIO ioDrive because there is no public pricing available for it – something I never understand and personally when companies do this I immediately think what are they hiding, luckily in FusionIO’s case the product is proven though is expensive compared to OCZ enterprise offerings. On the face of it the single 15Krpm hard disk has a price per GB of £0.39, the SSD £3.86; this is what you will see in the press and this is what sales people will use in comparing the two technologies – do not be fooled by this bullshit people! What is the requirement? The requirement is the database will have a static size of 400GB kept static through archiving so growth and trim will balance the database size, the client requires resilience, there will be several hundred call centre staff querying the database where queries will read a small amount of data but there will be no hot spot in the data so the randomness will come across the entire 400GB of the database, estimates predict that the IOps required will be approximately 4,000IOps at peak times, because it’s a call centre system the IO latency is important and must remain below 5ms per IO. The balance between read and write is 70% read, 30% write. The requirement is now defined and we have three of the most important pieces of the puzzle – space required, estimated IOps and maximum latency per IO. Something to consider with regard SQL Server; write activity requires synchronous IO to the storage media specifically the transaction log; that means the write thread will wait until the IO is completed and hardened off until the thread can continue execution, the requirement has stated that 30% of the system activity will be write so we can expect a high amount of synchronous activity. The hardware solution needs to be defined; two possible solutions: hard disk or solid state based; the real question now is how many hard disks are required to achieve the IO throughput, the latency and resilience, ditto for the solid state. Hard Drive solution On a test on an HP DL380, P410i controller using IOMeter against a single 15Krpm 146GB SAS drive, the throughput given on a transfer size of 8KiB against a 40GiB file on a freshly formatted disk where the partition is the only partition on the disk thus the 40GiB file is on the outer edge of the drive so more sectors can be read before head movement is required: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 3,733 IOps at an average latency of 34.06ms (34 MiB/s). The same test was done on the same disk but the test file was 130GiB: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 528 IOps at an average latency of 217.49ms (4 MiB/s). From the result it is clear random performance gets worse as the disk fills up – I’m currently writing an article on short stroking which will cover this in detail. Given the work load is random in nature looking at the random performance of the single drive when only 40 GiB of the 146 GB is used gives near the IOps required but the latency is way out. Luckily I have tested 6 x 15Krpm 146GB SAS 15Krpm drives in a RAID 0 using the same test methodology, for the same test above on a 130 GiB for each drive added the performance boost is near linear, for each drive added throughput goes up by 5 MiB/sec, IOps by 700 IOps and latency reducing nearly 50% per drive added (172 ms, 94 ms, 65 ms, 47 ms, 37 ms, 30 ms). This is because the same 130GiB is spread out more as you add drives 130 / 1, 130 / 2, 130 / 3 etc. so implicit short stroking is occurring because there is less file on each drive so less head movement required. The best latency is still 30 ms but we have the IOps required now, but that’s on a 130GiB file and not the 400GiB we need. Some reality check here: a) the drive randomness is more likely to be 50/50 and not a full 100% but the above has highlighted the effect randomness has on the drive and the more a drive fills with data the worse the effect. For argument sake let us assume that for the given workload we need 8 disks to do the job, for resilience reasons we will need 16 because we need to RAID 1+0 them in order to get the throughput and the resilience, RAID 5 would degrade performance. Cost for hard drives: 16 x £239.60 = £3,833.60 For the hard drives we will need disk controllers and a separate external disk array because the likelihood is that the server itself won’t take the drives, a quick spec off DELL for a PowerVault MD1220 which gives the dual pathing with 16 disks 146GB 15Krpm 2.5” disks is priced at £7,438.00, note its probably more once we had two controller cards to sit in the server in, racking etc. Minimum cost taking the DELL quote as an example is therefore: {Cost of Hardware} / {Storage Required} £7,438.60 / 400 = £18.595 per GB £18.59 per GiB is a far cry from the £0.39 we had been told by the salesman and the myth. Yes, the storage array is composed of 16 x 146 disks in RAID 10 (therefore 8 usable) giving an effective usable storage availability of 1168GB but the actual storage requirement is only 400 and the extra disks have had to be purchased to get the  IOps up. Solid State Drive solution A single card significantly exceeds the IOps and latency required, for resilience two will be required. ( £2,316.54 * 2 ) / 400 = £11.58 per GB With the SSD solution only two PCIe sockets are required, no external disk units, no additional controllers, no redundant controllers etc. Conclusion I hope by showing you an example that the myth that hard disk drives are cheaper per GiB than Solid State has now been dispelled - £11.58 per GB for SSD compared to £18.59 for Hard Disk. I’ve not even touched on the running costs, compare the costs of running 18 hard disks, that’s a lot of heat and power compared to two PCIe cards!Just a quick note: I've left a fair amount of information out due to this being a blog! If in doubt, email me :)I'll also deal with the myth that SSD's wear out at a later date as well - that's just way over done still, yes, 5 years ago, but now - no.

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  • Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error.

    - by Kp
    I get the following error in Chrome every time I try to run my script on a Linux server: Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error. In Firefox it just shows a blank white page. Whenever I run it on my local test server (IIS on Windows 7) it runs exactly the way it should with no errors. I am pretty sure that it is a problem with the imap_open function. error_reporting(E_ALL); echo "test"; // enter gmail username below e.g.-- $m_username = "yourusername"; $m_username = "username"; // enter gmail password below e.g.-- $m_password = "yourpword"; $m_password = "password"; // Enter the mail server to connect to $server = '{imap.gmail.com:993/imap/ssl/novalidate-cert}INBOX'; // enter the number of unread messages you want to display from mailbox or //enter 0 to display all unread messages e.g.-- $m_acs = 0; $m_acs = 10; // How far back in time do you want to search for unread messages - one month = 0 , two weeks = 1, one week = 2, three days = 3, // one day = 4, six hours = 5 or one hour = 6 e.g.-- $m_t = 6; $m_t = 2; //-----------Nothing More to edit below //open mailbox $m_mail = imap_open ($server, $m_username . "@gmail.com", $m_password) // or throw an error or die("ERROR: " . imap_last_error()); // unix time gone by $m_gunixtp = array(2592000, 1209600, 604800, 259200, 86400, 21600, 3600); // Date to start search $m_gdmy = date('d-M-Y', time() - $m_gunixtp[$m_t]); //search mailbox for unread messages since $m_t date $m_search=imap_search ($m_mail, 'ALL'); // Order results starting from newest message rsort($m_search); //if m_acs 0 then limit results if($m_acs 0){ array_splice($m_search, $m_acs); } $read = $_GET[read]; if ($read) { function get_mime_type(&$structure) { $primary_mime_type = array("TEXT", "MULTIPART","MESSAGE", "APPLICATION", "AUDIO","IMAGE", "VIDEO", "OTHER"); if($structure-subtype) { return $primary_mime_type[(int) $structure-type] . '/' .$structure-subtype; } return "TEXT/PLAIN"; } function get_part($stream, $msg_number, $mime_type, $structure = false,$part_number = false) { if(!$structure) { $structure = imap_fetchstructure($stream, $msg_number); } if($structure) { if($mime_type == get_mime_type($structure)) { if(!$part_number) { $part_number = "1"; } $text = imap_fetchbody($stream, $msg_number, $part_number); if($structure->encoding == 3) { return imap_base64($text); } else if($structure->encoding == 4) { return imap_qprint($text); } else { return $text; } } if($structure->type == 1) /* multipart */ { while(list($index, $sub_structure) = each($structure->parts)) { if($part_number) { $prefix = $part_number . '.'; } $data = get_part($stream, $msg_number, $mime_type, $sub_structure,$prefix . ($index + 1)); if($data) { return $data; } } // END OF WHILE } // END OF MULTIPART } // END OF STRUTURE return false; } // END OF FUNCTION // GET TEXT BODY $dataTxt = get_part($m_mail, $read, "TEXT/PLAIN"); // GET HTML BODY $dataHtml = get_part($m_mail, $read, "TEXT/HTML"); if ($dataHtml != "") { $msgBody = $dataHtml; $mailformat = "html"; } else { $msgBody = ereg_replace("\n","",$dataTxt); $mailformat = "text"; } if ($mailformat == "text") { echo "<html><head><title>Messagebody</title></head><body bgcolor=\"white\">$msgBody</body></html>"; } else { echo $msgBody; // It contains all HTML HEADER tags so we don't have to make them. } exit; } //loop it foreach ($m_search as $what_ever) { //get imap header info for obj thang $obj_thang = imap_headerinfo($m_mail, $what_ever); //get body info for obj thang $obj_thangs = imap_body($m_mail, $what_ever); //Then spit it out below.........if you dont swallow echo "Message ID# " . $what_ever . " Date: " . date("F j, Y, g:i a", $obj_thang-udate) . " From: " . $obj_thang-fromaddress . " To: " . $obj_thang-toaddress . " Subject: " . $obj_thang-Subject . " "; } echo "" . $m_empty . ""; //close mailbox imap_close($m_mail); ?

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  • The remote server returned an error: (400) Bad Request - uploading less 2MB file size?

    - by fiberOptics
    The file succeed to upload when it is 2KB or lower in size. The main reason why I use streaming is to be able to upload file up to at least 1 GB. But when I try to upload file with less 1MB size, I get bad request. It is my first time to deal with downloading and uploading process, so I can't easily find the cause of error. Testing part: private void button24_Click(object sender, EventArgs e) { try { OpenFileDialog openfile = new OpenFileDialog(); if (openfile.ShowDialog() == System.Windows.Forms.DialogResult.OK) { string port = "3445"; byte[] fileStream; using (FileStream fs = new FileStream(openfile.FileName, FileMode.Open, FileAccess.Read, FileShare.Read)) { fileStream = new byte[fs.Length]; fs.Read(fileStream, 0, (int)fs.Length); fs.Close(); fs.Dispose(); } string baseAddress = "http://localhost:" + port + "/File/AddStream?fileID=9"; HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(baseAddress); request.Method = "POST"; request.ContentType = "text/plain"; //request.ContentType = "application/octet-stream"; Stream serverStream = request.GetRequestStream(); serverStream.Write(fileStream, 0, fileStream.Length); serverStream.Close(); using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) { int statusCode = (int)response.StatusCode; StreamReader reader = new StreamReader(response.GetResponseStream()); } } } catch (Exception ex) { MessageBox.Show(ex.Message); } } Service: [WebInvoke(UriTemplate = "AddStream?fileID={fileID}", Method = "POST", BodyStyle = WebMessageBodyStyle.Bare)] public bool AddStream(long fileID, System.IO.Stream fileStream) { ClasslLogic.FileComponent svc = new ClasslLogic.FileComponent(); return svc.AddStream(fileID, fileStream); } Server code for streaming: namespace ClasslLogic { public class StreamObject : IStreamObject { public bool UploadFile(string filename, Stream fileStream) { try { FileStream fileToupload = new FileStream(filename, FileMode.Create); byte[] bytearray = new byte[10000]; int bytesRead, totalBytesRead = 0; do { bytesRead = fileStream.Read(bytearray, 0, bytearray.Length); totalBytesRead += bytesRead; } while (bytesRead > 0); fileToupload.Write(bytearray, 0, bytearray.Length); fileToupload.Close(); fileToupload.Dispose(); } catch (Exception ex) { throw new Exception(ex.Message); } return true; } } } Web config: <system.serviceModel> <bindings> <basicHttpBinding> <binding> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="2097152" maxBytesPerRead="4096" maxNameTableCharCount="2097152" /> <security mode="None" /> </binding> <binding name="ClassLogicBasicTransfer" closeTimeout="00:05:00" openTimeout="00:05:00" receiveTimeout="00:15:00" sendTimeout="00:01:00" allowCookies="false" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="67108864" maxReceivedMessageSize="67108864" messageEncoding="Mtom" textEncoding="utf-8" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="67108864" maxBytesPerRead="4096" maxNameTableCharCount="67108864" /> <security mode="None"> <transport clientCredentialType="None" proxyCredentialType="None" realm="" /> <message clientCredentialType="UserName" algorithmSuite="Default" /> </security> </binding> <binding name="BaseLogicWSHTTP"> <security mode="None" /> </binding> <binding name="BaseLogicWSHTTPSec" /> </basicHttpBinding> </bindings> <behaviors> <serviceBehaviors> <behavior> <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --> <serviceMetadata httpGetEnabled="true" /> <!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information --> <serviceDebug includeExceptionDetailInFaults="true" /> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment multipleSiteBindingsEnabled="true" aspNetCompatibilityEnabled="true" /> </system.serviceModel> I'm not sure if this affects the streaming function, because I'm using WCF4.0 rest template which config is dependent in Global.asax. One more thing is this, whether I run the service and passing a stream or not, the created file always contain this thing. How could I remove the "NUL" data? Thanks in advance. Edit public bool UploadFile(string filename, Stream fileStream) { try { FileStream fileToupload = new FileStream(filename, FileMode.Create); byte[] bytearray = new byte[10000]; int bytesRead, totalBytesRead = 0; do { bytesRead = fileStream.Read(bytearray, totalBytesRead, bytearray.Length - totalBytesRead); totalBytesRead += bytesRead; } while (bytesRead > 0); fileToupload.Write(bytearray, 0, totalBytesRead); fileToupload.Close(); fileToupload.Dispose(); } catch (Exception ex) { throw new Exception(ex.Message); } return true; }

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  • NUMA-aware placement of communication variables

    - by Dave
    For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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  • Completing install of ruby 1.9.3 with Ruby for for Mac OS X 10.7.5 Leopard, Xcode 4.5.2 -- problems with rvm pkg install openssl

    - by user1848361
    First, many thanks in advance for any help. I'm a complete novice with programming and I'm trying to get started with this Ruby on Rails tutorial (http://ruby.railstutorial.org/ruby-on-rails-tutorial-book?version=3.2) I have been trying figure this out for about 7 hours now and since I don't have any hair left to pull out I'm turning to these hallowed pages. I have searched for solutions here again and again. System: Mac OS X 10.7.5 Leopard, Xcode 4.5.2 I installed homebrew and have updated it multiple times I used homebrew to install rvm and have updated it multiple times I installed git The standard ruby on the system (checking with $ ruby -v) is 1.8.7 My problem is that every time I try to use rvm to install a new version of Ruby ($ rvm install 1.9.3) I get the following error: Ruby (and needed base gems) for your selection will be installed shortly. Before it happens, please read and execute the instructions below. Please use a separate terminal to execute any additional commands. Notes for Mac OS X 10.7.5, Xcode 4.5.2. For JRuby: Install the JDK. See http://developer.apple.com/java/download/ # Current Java version "1.6.0_26" For IronRuby: Install Mono >= 2.6 For Ruby 1.9.3: Install libksba # If using Homebrew, 'brew install libksba' For Opal: Install Nodejs with NPM. See http://nodejs.org/download/ To use an RVM installed Ruby as default, instead of the system ruby: rvm install 1.8.7 # installs patch 357: closest supported version rvm system ; rvm gemset export system.gems ; rvm 1.8.7 ; rvm gemset import system.gems # migrate your gems rvm alias create default 1.8.7 And reopen your terminal windows. Xcode and gcc: : I have performed $ brew install libksba and when I try to do it again it tells me that libksba is installed already. When I type "$ rvm requirements" I get: Notes for Mac OS X 10.7.5, Xcode 4.5.2. For JRuby: Install the JDK. See http://developer.apple.com/java/download/ # Current Java version "1.6.0_26" For IronRuby: Install Mono >= 2.6 For Ruby 1.9.3: Install libksba # If using Homebrew, 'brew install libksba' For Opal: Install Nodejs with NPM. See http://nodejs.org/download/ To use an RVM installed Ruby as default, instead of the system ruby: rvm install 1.8.7 # installs patch 357: closest supported version rvm system ; rvm gemset export system.gems ; rvm 1.8.7 ; rvm gemset import system.gems # migrate your gems rvm alias create default 1.8.7 And reopen your terminal windows. Xcode and gcc: Right now Ruby requires gcc to compile, but Xcode 4.2 and later no longer ship with gcc. Instead they ship with llvm-gcc (to which gcc is a symlink) and clang, neither of which are supported for building Ruby. Xcode 4.1 was the last version to ship gcc, which was /usr/bin/gcc-4.2. Xcode 4.1 and earlier: - Ruby will build fine. Xcode 4.2 and later (including Command Line Tools for Xcode): - If you have gcc-4.2 (and friends) from an earlier Xcode version, Ruby will build fine. - If you don't have gcc-4.2, you have two options to get it: * Install apple-gcc42 from Homebrew * Install osx-gcc-installer Homebrew: If you are using Homebrew, you can install the apple-gcc42 and required libraries from homebrew/dupes: brew update brew tap homebrew/dupes brew install autoconf automake apple-gcc42 rvm pkg install openssl Xcode 4.2+ install or/and Command Line Tools for Xcode is required to provide make and other tools. osx-gcc-installer: If you don't use Homebrew, you can download and install osx-gcc-installer: https://github.com/kennethreitz/osx-gcc-installer. Warning: Installing osx-gcc-installer on top of a recent Xcode is known to cause problems, so you must uninstall Xcode before installing osx-gcc-installer. Afterwards you may install Xcode 4.2+ or Command Line Tools for Xcode if you desire. ** NOTE: Currently, Node.js is having issues building with osx-gcc-installer. The only fix is to install Xcode over osx-gcc-installer. So I assume I have to do something with brew update brew tap homebrew/dupes brew install autoconf automake apple-gcc42 rvm pkg install openssl Everything seemed to work fine until "$ rvm pkg install openssl", which returns: Fetching openssl-1.0.1c.tar.gz to /Users/thierinvestmentservices/.rvm/archives Extracting openssl to /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c Configuring openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Compiling openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Error running 'make', please read /Users/thierinvestmentservices/.rvm/log/openssl/make.log Please note that it's required to reinstall all rubies: rvm reinstall all --force Updating openssl certificates Error running 'update_openssl_certs', please read /Users/thierinvestmentservices/.rvm/log/openssl.certs.log Johns-MacBook-Pro:~ thierinvestmentservices$ rvm pkg install openssl Fetching openssl-1.0.1c.tar.gz to /Users/thierinvestmentservices/.rvm/archives Extracting openssl to /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c Configuring openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Compiling openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Error running 'make', please read /Users/thierinvestmentservices/.rvm/log/openssl/make.log Please note that it's required to reinstall all rubies: rvm reinstall all --force Updating openssl certificates Error running 'update_openssl_certs', please read /Users/thierinvestmentservices/.rvm/log/openssl.certs.log make.log reads "[2012-11-23 13:15:28] make /Users/thierinvestmentservices/.rvm/scripts/functions/utility: line 116: make: command not found" and openssl.certs.log reads "[2012-11-23 14:04:04] update_openssl_certs update_openssl_certs () { ( chpwd_functions="" builtin cd $rvm_usr_path/ssl && command curl -O http://curl.haxx.se/ca/cacert.pem && mv cacert.pem cert.pem ) } current path: /Users/thierinvestmentservices command(1): update_openssl_certs /Users/thierinvestmentservices/.rvm/scripts/functions/pkg: line 205: cd: /Users/thierinvestmentservices/.rvm/usr/ssl: No such file or directory" At this point the letters might as well be wingdings I have no idea what is going on. I have tried to install rvm make with something I saw on one forum post but I got a bunch of warnings. If anyone has any suggestions I would be deeply grateful, I am completely in over my head,

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  • Super constructor must be a first statement in Java constructor [closed]

    - by Val
    I know the answer: "we need rules to prevent shooting into your own foot". Ok, I make millions of programming mistakes every day. To be prevented, we need one simple rule: prohibit all JLS and do not use Java. If we explain everything by "not shooting your foot", this is reasonable. But there is not much reason is such reason. When I programmed in Delphy, I always wanted the compiler to check me if I read uninitializable. I have discovered myself that is is stupid to read uncertain variable because it leads unpredictable result and is errorenous obviously. By just looking at the code I could see if there is an error. I wished if compiler could do this job. It is also a reliable signal of programming error if function does not return any value. But I never wanted it do enforce me the super constructor first. Why? You say that constructors just initialize fields. Super fields are derived; extra fields are introduced. From the goal point of view, it does not matter in which order you initialize the variables. I have studied parallel architectures and can say that all the fields can even be assigned in parallel... What? Do you want to use the unitialized fields? Stupid people always want to take away our freedoms and break the JLS rules the God gives to us! Please, policeman, take away that person! Where do I say so? I'm just saying only about initializing/assigning, not using the fields. Java compiler already defends me from the mistake of accessing notinitialized. Some cases sneak but this example shows how this stupid rule does not save us from the read-accessing incompletely initialized in construction: public class BadSuper { String field; public String toString() { return "field = " + field; } public BadSuper(String val) { field = val; // yea, superfirst does not protect from accessing // inconstructed subclass fields. Subclass constr // must be called before super()! System.err.println(this); } } public class BadPost extends BadSuper { Object o; public BadPost(Object o) { super("str"); this. o = o; } public String toString() { // superconstructor will boom here, because o is not initialized! return super.toString() + ", obj = " + o.toString(); } public static void main(String[] args) { new BadSuper("test 1"); new BadPost(new Object()); } } It shows that actually, subfields have to be inilialized before the supreclass! Meantime, java requirement "saves" us from writing specializing the class by specializing what the super constructor argument is, public class MyKryo extends Kryo { class MyClassResolver extends DefaultClassResolver { public Registration register(Registration registration) { System.out.println(MyKryo.this.getDepth()); return super.register(registration); } } MyKryo() { // cannot instantiate MyClassResolver in super super(new MyClassResolver(), new MapReferenceResolver()); } } Try to make it compilable. It is always pain. Especially, when you cannot assign the argument later. Initialization order is not important for initialization in general. I could understand that you should not use super methods before initializing super. But, the requirement for super to be the first statement is different. It only saves you from the code that does useful things simply. I do not see how this adds safety. Actually, safety is degraded because we need to use ugly workarounds. Doing post-initialization, outside the constructors also degrades safety (otherwise, why do we need constructors?) and defeats the java final safety reenforcer. To conclude Reading not initialized is a bug. Initialization order is not important from the computer science point of view. Doing initalization or computations in different order is not a bug. Reenforcing read-access to not initialized is good but compilers fail to detect all such bugs Making super the first does not solve the problem as it "Prevents" shooting into right things but not into the foot It requires to invent workarounds, where, because of complexity of analysis, it is easier to shoot into the foot doing post-initialization outside the constructors degrades safety (otherwise, why do we need constructors?) and that degrade safety by defeating final access modifier When there was java forum alive, java bigots attecked me for these thoughts. Particularly, they dislaked that fields can be initialized in parallel, saying that natural development ensures correctness. When I replied that you could use an advanced engineering to create a human right away, without "developing" any ape first, and it still be an ape, they stopped to listen me. Cos modern technology cannot afford it. Ok, Take something simpler. How do you produce a Renault? Should you construct an Automobile first? No, you start by producing a Renault and, once completed, you'll see that this is an automobile. So, the requirement to produce fields in "natural order" is unnatural. In case of alarmclock or armchair, which are still chair and clock, you may need first develop the base (clock and chair) and then add extra. So, I can have examples where superfields must be initialized first and, oppositely, when they need to be initialized later. The order does not exist in advance. So, the compiler cannot be aware of the proper order. Only programmer/constructor knows is. Compiler should not take more responsibility and enforce the wrong order onto programmer. Saying that I cannot initialize some fields because I did not ininialized the others is like "you cannot initialize the thing because it is not initialized". This is a kind of argument we have. So, to conclude once more, the feature that "protects" me from doing things in simple and right way in order to enforce something that does not add noticeably to the bug elimination at that is a strongly negative thing and it pisses me off, altogether with the all the arguments to support it I've seen so far. It is "a conceptual question about software development" Should there be the requirement to call super() first or not. I do not know. If you do or have an idea, you have place to answer. I think that I have provided enough arguments against this feature. Lets appreciate the ones who benefit form it. Let it just be something more than simple abstract and stupid "write your own language" or "protection" kind of argument. Why do we need it in the language that I am going to develop?

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  • Passing a parameter so that it cannot be changed – C#

    - by nmarun
    I read this requirement of not allowing a user to change the value of a property passed as a parameter to a method. In C++, as far as I could recall (it’s been over 10 yrs, so I had to refresh memory), you can pass ‘const’ to a function parameter and this ensures that the parameter cannot be changed inside the scope of the function. There’s no such direct way of doing this in C#, but that does not mean it cannot be done!! Ok, so this ‘not-so-direct’ technique depends on the type of the parameter – a simple property or a collection. Parameter as a simple property: This is quite easy (and you might have guessed it already). Bulent Ozkir clearly explains how this can be done here. Parameter as a collection property: Obviously the above does not work if the parameter is a collection of some type. Let’s dig-in. Suppose I need to create a collection of type KeyTitle as defined below. 1: public class KeyTitle 2: { 3: public int Key { get; set; } 4: public string Title { get; set; } 5: } My class is declared as below: 1: public class Class1 2: { 3: public Class1() 4: { 5: MyKeyTitleList = new List<KeyTitle>(); 6: } 7: 8: public List<KeyTitle> MyKeyTitleList { get; set; } 9: public ReadOnlyCollection<KeyTitle> ReadonlyKeyTitleCollection 10: { 11: // .AsReadOnly creates a ReadOnlyCollection<> type 12: get { return MyKeyTitleList.AsReadOnly(); } 13: } 14: } See the .AsReadOnly() method used in the second property? As MSDN says it: “Returns a read-only IList<T> wrapper for the current collection.” Knowing this, I can implement my code as: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8:  9: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 10:  11: Console.ReadLine(); 12: } 13:  14: private static void TryToModifyCollection(ReadOnlyCollection<KeyTitle> readOnlyCollection) 15: { 16: // can only read 17: for (int i = 0; i < readOnlyCollection.Count; i++) 18: { 19: Console.WriteLine("{0} - {1}", readOnlyCollection[i].Key, readOnlyCollection[i].Title); 20: } 21: // Add() - not allowed 22: // even the indexer does not have a setter 23: } The output is as expected: The below image shows two things. In the first line, I’ve tried to access an element in my read-only collection through an indexer. It shows that the ReadOnlyCollection<> does not have a setter on the indexer. The second line tells that there’s no ‘Add()’ method for this type of collection. The capture below shows there’s no ‘Remove()’ method either, there-by eliminating all ways of modifying a collection. Mission accomplished… right? Now, even if you have a collection of different type, all you need to do is to somehow cast (used loosely) it to a List<> and then do a .AsReadOnly() to get a ReadOnlyCollection of your custom collection type. As an example, if you have an IDictionary<int, string>, you can create a List<T> of this type with a wrapper class (KeyTitle in our case). 1: public IDictionary<int, string> MyDictionary { get; set; } 2:  3: public ReadOnlyCollection<KeyTitle> ReadonlyDictionary 4: { 5: get 6: { 7: return (from item in MyDictionary 8: select new KeyTitle 9: { 10: Key = item.Key, 11: Title = item.Value, 12: }).ToList().AsReadOnly(); 13: } 14: } Cool huh? Just one thing you need to know about the .AsReadOnly() method is that the only way to modify your ReadOnlyCollection<> is to modify the original collection. So doing: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 9:  10: Console.WriteLine(); 11:  12: class1.MyKeyTitleList.Add(new KeyTitle { Key = 5, Title = "mno" }); 13: class1.MyKeyTitleList[2] = new KeyTitle{Key = 3, Title = "GHI"}; 14: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 15:  16: Console.ReadLine(); 17: } Gives me the output of: See that the second element’s Title is changed to upper-case and the fifth element also gets displayed even though we’re still looping through the same ReadOnlyCollection<KeyTitle>. Verdict: Now you know of a way to implement ‘Method(const param1)’ in your code!

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  • I asked this yesterday, after the input given I'm still having trouble implementing..

    - by Josh
    I'm not sure how to fix this or what I did wrong, but whenever I enter in a value it just closes out the run prompt. So, seems I do have a problem somewhere in my coding. Whenever I run the program and input a variable, it always returns the same answer.."The content at location 76 is 0." On that note, someone told me that "I don't know, but I suspect that Program A incorrectly has a fixed address being branched to on instructions 10 and 11." - mctylr but I'm not sure how to fix that.. I'm trying to figure out how to incorporate this idea from R Samuel Klatchko.. I'm still not sure what I'm missing but I can't get it to work.. const int OP_LOAD = 3; const int OP_STORE = 4; const int OP_ADD = 5; ... const int OP_LOCATION_MULTIPLIER = 100; mem[0] = OP_LOAD * OP_LOCATION_MULTIPLIER + ...; mem[1] = OP_ADD * OP_LOCATION_MULTIPLIER + ...; operand = memory[ j ] % OP_LOCATION_MULTIPLIER; operation = memory[ j ] / OP_LOCATION_MULTIPLIER; I'm new to programming, I'm not the best, so I'm going for simplicity. Also this is an SML program. Anyway, this IS a homework assignment and I'm wanting a good grade on this. So I was looking for input and making sure this program will do what I'm hoping they are looking for. Anyway, here are the instructions: Write SML (Simpletron Machine language) programs to accomplish each of the following task: A) Use a sentinel-controlled loop to read positive number s and compute and print their sum. Terminate input when a neg number is entered. B) Use a counter-controlled loop to read seven numbers, some positive and some negative, and compute + print the avg. C) Read a series of numbers, and determine and print the largest number. The first number read indicates how many numbers should be processed. Without further a due, here is my program. All together. int main() { const int READ = 10; const int WRITE = 11; const int LOAD = 20; const int STORE = 21; const int ADD = 30; const int SUBTRACT = 31; const int DIVIDE = 32; const int MULTIPLY = 33; const int BRANCH = 40; const int BRANCHNEG = 41; const int BRANCHZERO = 41; const int HALT = 43; int mem[100] = {0}; //Making it 100, since simpletron contains a 100 word mem. int operation; //taking the rest of these variables straight out of the book seeing as how they were italisized. int operand; int accum = 0; // the special register is starting at 0 int j; // This is for part a, it will take in positive variables in a sent-controlled loop and compute + print their sum. Variables from example in text. memory [0] = 1010; memory [01] = 2009; memory [02] = 3008; memory [03] = 2109; memory [04] = 1109; memory [05] = 4300; memory [06] = 1009; j = 0; //Makes the variable j start at 0. while ( true ) { operand = memory[ j ]%100; // Finds the op codes from the limit on the memory (100) operation = memory[ j ]/100; //using a switch loop to set up the loops for the cases switch ( operation ){ case 10: //reads a variable into a word from loc. Enter in -1 to exit cout <<"\n Input a positive variable: "; cin >> memory[ operand ]; break; case 11: // takes a word from location cout << "\n\nThe content at location " << operand << "is " << memory[operand]; break; case 20:// loads accum = memory[ operand ]; break; case 21: //stores memory[ operand ] = accum; break; case 30: //adds accum += mem[operand]; break; case 31: // subtracts accum-= memory[ operand ]; break; case 32: //divides accum /=(memory[ operand ]); break; case 33: // multiplies accum*= memory [ operand ]; break; case 40: // Branches to location j = -1; break; case 41: //branches if acc. is < 0 if (accum < 0) j = 5; break; case 42: //branches if acc = 0 if (accum == 0) j = 5; break; case 43: // Program ends exit(0); break; } j++; } return 0; }

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 4

    - by MarkPearl
    Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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  • SimpleXMLElement empty object

    - by Mike
    Hi, I am trying to parse an xml file using XmlReader but although I am getting a return from the xml file for the (commission) node for some reason I am getting an empty SimpleXMLElement Object returned as well. I don't know if its something to do with while loop,switch or something I missed in the parse setup. This is the xml file I am trying to read from, as you can see there is only 1 result returned: <?xml version="1.0" encoding="UTF-8"?> <cj-api> <commissions total-matched="1"> <commission> <action-status> new </action-status> <action-type> lead </action-type> <aid> 10730981 </aid> <commission-id> 1021015513 </commission-id> <country> </country> <event-date> 2010-05-08T08:08:55-0700 </event-date> <locking-date> 2010-06-10 </locking-date> <order-id> 345007 </order-id> <original> true </original> <original-action-id> 787692438 </original-action-id> <posting-date> 2010-05-08T10:01:22-0700 </posting-date> <website-id> 3201921 </website-id> <cid> 2815954 </cid> <advertiser-name> SPS EurosportBET </advertiser-name> <commission-amount> 0 </commission-amount> <order-discount> 0 </order-discount> <sid> 0 </sid> <sale-amount> 0 </sale-amount> </commission> </commissions> </cj-api> This is my parser: <?php // read $response (xml feed) $file = "datafeed.xml"; $xml = new XMLReader; $xml->open($file); // loop to read in data while ($xml->read()) { switch ($xml->name) { // find the parent node for each commission payment case 'commission': // initalise xml parser $dom = new DomDocument(); $dom_node = $xml ->expand(); $element = $dom->appendChild($dom_node); $dom_string = $dom->saveXML($element); $commission = new SimpleXMLElement($dom_string); // read in data $action_status = $commission->{'action-status'}; $action_type = $commission->{'action-type'}; $aid = $commission->{'aid'}; $commission_id = $commission->{'commission-id'}; $country = $commission->{'country'}; $event_date = $commission->{'event-date'}; $locking_date = $commission->{'locking-date'}; $order_id = $commission->{'order-id'}; $original = $commission->{'original'}; $original_action_id = $commission->{'original_action-id'}; $posting_date = $commission->{'posting-date'}; $website_id = $commission->{'website-id'}; $cid = $commission->{'cid'}; $advertiser_name = $commission->{'advertiser-name'}; $commission_amount = $commission->{'commission-amount'}; $order_discount = $commission->{'order-discount'}; $sid = $commission->{'sid'}; $sale_amount = $commission->{'sale-amount'}; print_r($aid); break; } } ?> The result is : SimpleXMLElement Object ( [0] => 10730981 ) SimpleXMLElement Object ( ) Why is it returning the second object: SimpleXMLElement Object ( ) and what do I need to do correct it? Thanks.

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