thread local storage - Page 17

localtime_r supposed to be thread safe, but causing errors in Valgrind DRD

- by Nik

I searched google as much as I could but I couldn't find any good answers to this. localtime_r is supposed to be a thread-safe function for getting the system time. However, when checking my application with Valgrind --tool=drd, it consistantly tells me that there is a data race condition on this function. Are the common search results lying to me, or am I just missing something? It doesn't seem efficient to surround each localtime_r call with a mutex, especially if it is supposed to by thread safe in the first place. here is how i'm using it: timeval handlerTime; gettimeofday(&handlerTime,NULL); tm handlerTm; localtime_r(&handlerTime.tv_sec,&handlerTm); Any ideas?

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[WPF] The calling thread cannot access this object because a different thread owns it.

- by zunyite

Why I can't create CroppedBitmap in the following code ? I got an exception : The calling thread cannot access this object because a different thread owns it. public MainWindow() { InitializeComponent(); ThreadPool.QueueUserWorkItem((o) => { //load a large image file var bf = BitmapFrame.Create( new Uri("D:\\1172735642.jpg"), BitmapCreateOptions.DelayCreation | BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.None); bf.Freeze(); Dispatcher.BeginInvoke( new Action(() => { CroppedBitmap cb = new CroppedBitmap(bf, new Int32Rect(1,1,5,5)); cb.Freeze(); //set Image's source to cb.... }), System.Windows.Threading.DispatcherPriority.ApplicationIdle); } ); }

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Java Thread - Synchronization issue

- by Yatendra Goel

From Sun's tutorial: Synchronized methods enable a simple strategy for preventing thread interference and memory consistency errors: if an object is visible to more than one thread, all reads or writes to that object's variables are done through synchronized methods. (An important exception: final fields, which cannot be modified after the object is constructed, can be safely read through non-synchronized methods, once the object is constructed) This strategy is effective, but can present problems with liveness, as we'll see later in this lesson. Q1. Is the above statements mean that if an object of a class is going to be shared among multiple threads, then all instance methods of that class (except getters of final fields) should be made synchronized, since instance methods process instance variables?

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what is difference between fork and thread

- by pavun_cool

Hi All, Can you any one explain me about what is difference between fork and thread ..? Thanks

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Python Threading, loading one thread after another

- by Michael

Hi, I'm working on a media player and am able to load in a single .wav and play it. As seen in the code below. foo = wx.FileDialog(self, message="Open a .wav file...", defaultDir=os.getcwd(), defaultFile="", style=wx.FD_MULTIPLE) foo.ShowModal() queue = foo.GetPaths() self.playing_thread = threading.Thread(target=self.playFile, args=(queue[0], 'msg')) self.playing_thread.start() But the problem is, when I try to make the above code into a loop for multiple .wav files. Such that while playing_thread.isActive == True, create and .start() the thread. Then if .isActive == False, pop queue[0] and load the next .wav file. Problem is, my UI will lock up and I'll have to terminate the program. Any ideas would be appreciated.

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Static dictionary in .Net Thread safety

- by Emmanuel

Reading msdn documentation for dictionaries it says : "Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe." Those this mean that with a dictionary such as this : static object syncObject = new object(); static Dictionary<string,MyObject> mydictionary= new Dictionary<string, MyObject>(); Is doing something like the code below unnecessary? lock (syncObject) { context = new TDataContext(); mydictionary.Add("key", myObject); }

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Help ! Flex Local connection

- by jonny

Hi all , i was building an application that use local connection and listens to another application that also uses local connection , the second application is sort of remote control for the first app. it invokes function of the listening app from outside. anyway , everything works good on local host. BUT once i have put the listening app on a server and try to work it , it does not connect anymore. any idea's? Thanks

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Optimal strategy to make a C++ hash table, thread safe

- by Ajeet

(I am interested in design of implementation NOT a readymade construct that will do it all.) Suppose we have a class HashTable (not hash-map implemented as a tree but hash-table) and say there are eight threads. Suppose read to write ratio is about 100:1 or even better 1000:1. Case A) Only one thread is a writer and others including writer can read from HashTable(they may simply iterate over entire hash table) Case B) All threads are identical and all could read/write. Can someone suggest best strategy to make the class thread safe with following consideration 1. Top priority to least lock contention 2. Second priority to least number of locks My understanding so far is thus : One BIG reader-writer lock(semaphore). Specialize the semaphore so that there could be eight instances writer-resource for case B, where each each writer resource locks one row(or range for that matter). (so i guess 1+8 mutexes) Please let me know if I am thinking on the correct line, and how could we improve on this solution.

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OIM 11g : Multi-thread approach for writing custom scheduled job

- by Saravanan V S

In this post I have shared my experience of designing and developing an OIM schedule job that uses multi threaded approach for updating data in OIM using APIs. I have used thread pool (in particular fixed thread pool) pattern in developing the OIM schedule job. The thread pooling pattern has noted advantages compared to thread per task approach. I have listed few of the advantage here · Threads are reused · Creation and tear-down cost of thread is reduced · Task execution latency is reduced · Improved performance · Controlled and efficient management of memory and resources used by threads More about java thread pool http://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html The following diagram depicts the high-level architectural diagram of the schedule job that process input from a flat file to update OIM process form data using fixed thread pool approach The custom scheduled job shared in this post is developed to meet following requirement 1) Need to process a CSV extract that contains identity, account identifying key and list of data to be updated on an existing OIM resource account. 2) CSV file can contain data for multiple resources configured in OIM 3) List of attribute to update and mapping between CSV column to OIM fields may vary between resources The following are three Java class developed for this requirement (I have given only prototype of the code that explains how to use thread pools in schedule task) CustomScheduler.java - Implementation of TaskSupport class that reads and passes the parameters configured on the schedule job to Thread Executor class. package com.oracle.oim.scheduler; import java.util.HashMap; import com.oracle.oim.bo.MultiThreadDataRecon; import oracle.iam.scheduler.vo.TaskSupport; public class CustomScheduler extends TaskSupport { public void execute(HashMap options) throws Exception { /* Read Schedule Job Parameters */ String param1 = (String) options.get(“Parameter1”); . int noOfThread = (int) options.get(“No of Threads”); . String paramn = (int) options.get(“ParamterN”); /* Provide all the required input configured on schedule job to Thread Pool Executor implementation class like 1) Name of the file, 2) Delimiter 3) Header Row Numer 4) Line Escape character 5) Config and resource map lookup 6) No the thread to create */ new MultiThreadDataRecon(all_required_parameters, noOfThreads).reconcile(); } public HashMap getAttributes() { return null; } public void setAttributes() { } } MultiThreadDataRecon.java – Helper class that reads data from input file, initialize the thread executor and builds the task queue. package com.oracle.oim.bo; import <required file IO classes>; import <required java.util classes>; import <required OIM API classes>; import <csv reader api>; public class MultiThreadDataRecon { private int noOfThreads; private ExecutorService threadExecutor = null; public MetaDataRecon(<required params>, int noOfThreads) { //Store parameters locally . . this.noOfThread = noOfThread; } /** * Initialize */ private void init() throws Exception { try { // Initialize CSV file reader API objects // Initialize OIM API objects /* Initialize Fixed Thread Pool Executor class if no of threads configured is more than 1 */ if (noOfThreads > 1) { threadExecutor = Executors.newFixedThreadPool(noOfThreads); } else { threadExecutor = Executors.newSingleThreadExecutor(); } /* Initialize TaskProcess clas s which will be executing task from the Queue */ TaskProcessor.initializeConfig(params); } catch (***Exception e) { // TO DO } } /** * Method to reconcile data from CSV to OIM */ public void reconcile() throws Exception { try { init(); while(<csv file has line>){ processRow(line); } /* Initiate thread shutdown */ threadExecutor.shutdown(); while (!threadExecutor.isTerminated()) { // Wait for all task to complete. } } catch (Exception e) { // TO DO } finally { try { //Close all the file handles } catch (IOException e) { //TO DO } } } /** * Method to process */ private void processRow(String row) { // Create task processor instance with the row data // Following code push the task to work queue and wait for next available thread to execute threadExecutor.execute(new TaskProcessor(rowData)); } } TaskProcessor.java – Implementation of “Runnable” interface that executes the required business logic to update data in OIM. package com.oracle.oim.bo; import <required APIs> class TaskProcessor implements Runnable { //Initialize required member variables /** * Constructor */ public TaskProcessor(<row data>) { // Initialize and parse csv row } /* * Method to initialize required object for task execution */ public static void initializeConfig(<params>) { // Process param and initialize the required configs and object } /* * (non-Javadoc) * * @see java.lang.Runnable#run() */ public void run() { if (<is csv data valid>){ processData(); } } /** * Process the the received CSV input */ private void processData() { try{ //Find the user in OIM using the identity matching key value from CSV // Find the account to be update from user’s account based on account identifying key on CSV // Update the account with data from CSV }catch(***Exception e){ //TO DO } } }

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Local User Login Script Fedora Linux

- by Sam

How do I allow a login script for one user in fedora? ~/.initrc doesn't seem to work, and I tried adding an executable to /etc/init.d but that's for all users (and it didnt work either anyway).

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Profiles and using the local profile for a domain user

- by Harry

I’m having some trouble with profiles and would like to reach out for some help. I’ve tried to do some research to help myself along, but I’m not making much progress on my own. I’ve pretty much taken over the sys admin duties for my small lab, I don’t have much experience to justify it besides I’m the only with the time and dedication to go at it (The environment was in a state of disrepair). My network and domain I look over are extremely small by most standards, about 10 users at a time. They are pretty intensive activity on the network, and we do work with fairly large files. None of the network is online, which is nice at the moment because it allows me not to have another headache. On to my profile problem, I have set up roaming profiles for the users in the network. Now after a little research, I think I will be switching this to a hybrid of folder redirection and roaming profiles as this seems to best practice. I also don’t want the users having to wait for a long time if they have a bloated profile. Now I’ve finally got a build working using MDT. We have Mac Pros, and it wasn’t fun getting everything to play nice. The way I did this was by setting up a reference computer and installing all the software and tools that each user would need and editing the settings preferences to how we would need them. I think used MDT to do a sys prep and capture to create the image of my reference computer. Using the reference image I can push out my images to the rest of the desktops in my environment. The issue I’m having is when we join the computer to domain. The user can login and operate fine on the computer, but I’d like a more. When the user is logged on with their domain user name they lose a lot of the icons I had on my reference image, as well as the desktop background and some other miscellaneous settings. I would love to have the user log on using their domain user name and see the icons and desktop environment as I had it setup on the reference computer. I’m not sure if it is possible, or something simple that I’m missing, but any help would be greatly appreciated!

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Local Area Connection in Slacware 13

- by asdasd

I have windows xp and slackware 13 on one computer, and the ISP provided me a new modem. There was manual how to configure it, so i start the web browser and typed it's ip address 192.168.1.1 and the web interface of the modem appeared so i logged in, that was easy. But under slackware, i don't know how to enter in the modem config / web interface. I type in 192.168.1.1 but it's not working. Here's the output of ifconfig eth0 : eth0 Link encap:Ethernet HWaddr 00:a1:b0:01:18:28 inet addr:169.254.73.8 Bcast:169.254.255.255 Mask:255.255.0.0 UP BROADCAST 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:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:17 Memory:febff400-febff4ff How can i log in into the modem from linux, i.e. find it's assigned ip under slackware ? Thank you.

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Sending mail to local address crashes web server (sendmail)

- by deceze

When trying to send mail automatically from a script at example.com via PHP's mail() to [email protected], the Apache server throws an Internal Error. I believe internally it is configured to use sendmail. The message gets dropped into ~/dead.letter and the general error log reads: [Wed May 12 11:26:45 2010] [error] [client xxx.xxx.xxx.xxx] malformed header from script. Bad header=/home/example/dead.letter... S: /home/example/www/test.php Trying any other address, not @example.com, works just fine. I have googled and serverfaulted for solutions, but they all require to edit configuration files in /etc/mail and similar system places, which is not an option, since this problem occurs on a shared host in which I only have access to ~/. Does anyone have a suggestion?

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Synchronizing local and remote cache in distributed caching

- by ltfishie

With a distributed cache, a subset of the cache is kept locally while the rest is held remotely. In a get operation, if the entry is not available locally, the remote cache will be used and and the entry is added to local cache. In a put operation, both the local cache and remote cache are updated. Other nodes in the cluster also need to be notified to invalidate their local cache as well. What's a simplest way to achieve this if you implemented it yourself, assuming that nodes are not aware of each other. Edit My current implementation goes like this: Each cache entry contains a time stamp. Put operation will update local cache and remote cache Get operation will try local cache then remote cache A background thread on each node will check remote cache periodically for each entry in local cache. If the timestamp on remote is newer overwrite the local. If entry is not found in remote, delete it from local.

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Is a 1:* write:read thread system safe?

- by Di-0xide

Theoretically, thread-safe code should fix race conditions. Race conditions, as I understand it, occur because two threads attempt to write to the same location at the same time. However, what about a threading model in which a single thread is designed to write to a location, and several slave/worker threads simply read from the location? Assuming the value/timing at which they read the data isn't relevant/doesn't hinder the worker thread's outcome, wouldn't this be considered 'thread safe', or am I missing something in my logic?

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ASUS WL-500gP v2 network between two local machines

- by Epsiloncool

I have two windows XP machines in my home networks, connected with ASUS WL-500gp V2 which also used as internet router. Problem is: while I have both computers normally goes to internet (used DHCP, static routes is ON, routing table is empty, operation mode is Home Gateway). I see both computers listed on the Network Neighborhood on 1st computer (wired to router), can enter to my own computer, but can not enter to other. I see only one computer (2nd) on the Network Neighborhood on 2nd computer (connected thru Wi-Fi), can enter to itself, getting error when trying to enter 1st computer address in address line (like \My1stComp). What is the problem? I totally crazy founding problem about 3 months.

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ZFS Storage Appliance ? ldap ??????

- by user13138569

ZFS Storage Appliance ? Openldap ????????? ???ldap ?????????????? Solaris 11 ? Openldap ????????????? ??? slapd.conf ??ldif ?????????? user01 ??????? ?????? slapd.conf # # See slapd.conf(5) for details on configuration options. # This file should NOT be world readable. # include /etc/openldap/schema/core.schema include /etc/openldap/schema/cosine.schema include /etc/openldap/schema/nis.schema # Define global ACLs to disable default read access. # Do not enable referrals until AFTER you have a working directory # service AND an understanding of referrals. #referral ldap://root.openldap.org pidfile /var/openldap/run/slapd.pid argsfile /var/openldap/run/slapd.args # Load dynamic backend modules: modulepath /usr/lib/openldap moduleload back_bdb.la # moduleload back_hdb.la # moduleload back_ldap.la # Sample security restrictions # Require integrity protection (prevent hijacking) # Require 112-bit (3DES or better) encryption for updates # Require 63-bit encryption for simple bind # security ssf=1 update_ssf=112 simple_bind=64 # Sample access control policy: # Root DSE: allow anyone to read it # Subschema (sub)entry DSE: allow anyone to read it # Other DSEs: # Allow self write access # Allow authenticated users read access # Allow anonymous users to authenticate # Directives needed to implement policy: # access to dn.base="" by * read # access to dn.base="cn=Subschema" by * read # access to * # by self write # by users read # by anonymous auth # # if no access controls are present, the default policy # allows anyone and everyone to read anything but restricts # updates to rootdn. (e.g., "access to * by * read") # # rootdn can always read and write EVERYTHING! ####################################################################### # BDB database definitions ####################################################################### database bdb suffix "dc=oracle,dc=com" rootdn "cn=Manager,dc=oracle,dc=com" # Cleartext passwords, especially for the rootdn, should # be avoid. See slappasswd(8) and slapd.conf(5) for details. # Use of strong authentication encouraged. rootpw secret # The database directory MUST exist prior to running slapd AND # should only be accessible by the slapd and slap tools. # Mode 700 recommended. directory /var/openldap/openldap-data # Indices to maintain index objectClass eq ?????????ldif???? dn: dc=oracle,dc=com objectClass: dcObject objectClass: organization dc: oracle o: oracle dn: cn=Manager,dc=oracle,dc=com objectClass: organizationalRole cn: Manager dn: ou=People,dc=oracle,dc=com objectClass: organizationalUnit ou: People dn: ou=Group,dc=oracle,dc=com objectClass: organizationalUnit ou: Group dn: uid=user01,ou=People,dc=oracle,dc=com uid: user01 objectClass: top objectClass: account objectClass: posixAccount objectClass: shadowAccount cn: user01 uidNumber: 10001 gidNumber: 10000 homeDirectory: /home/user01 userPassword: secret loginShell: /bin/bash shadowLastChange: 10000 shadowMin: 0 shadowMax: 99999 shadowWarning: 14 shadowInactive: 99999 shadowExpire: -1 ldap?????????????ZFS Storage Appliance??????? Configuration SERVICES LDAP ??Base search DN ?ldap??????????? ???? ldap ????????? user01 ???????????????? ???????????? user ????????? Unknown or invalid user ?????????????????? ????????????????Solaris 11 ???????????? ????????????? ldap ????????getent ??????????????? # svcadm enable svc:/network/nis/domain:default # svcadm enable ldap/client # ldapclient manual -a authenticationMethod=none -a defaultSearchBase=dc=oracle,dc=com -a defaultServerList=192.168.56.201 System successfully configured # getent passwd user01 user01:x:10001:10000::/home/user01:/bin/bash ????????? user01 ?????????????? # mount -F nfs -o vers=3 192.168.56.101:/export/user01 /mnt # su user01 bash-4.1$ cd /mnt bash-4.1$ touch aaa bash-4.1$ ls -l total 1 -rw-r--r-- 1 user01 10000 0 May 31 04:32 aaa ?????? ldap ??????????????????????????!

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What is Best storage servers infrastructure ? DAS/NAS/SAN or installing GlusterFS/LUSTER/HDFS/RBDB

- by TORr0t

I am trying to design an infrastucture for the project I am working on. It would be somehow a file-sharing/downloading project (like rapidshare) and I would need high storage sizes and good scability, and I would add new storage nodes after my project grows up. I have come up with 3 solutions for my project which are using Luster, GlusterFS, HDFS, RDBD. For start, i would have 2 servers, one server is for glusterfs client + webserver + db server+ a streaming server, and the other server is gluster storage node. (After sometime, i would be adding more node servers, and client servers (dont know how many new client new servers to add, will see later) So, i am thinking to work with glusterfs. But i really wonder that if i have to use high performance servers with high sotrage sizes or avarage/slow servers with high storage sizes? Or nas/das/san solutions are better for glusterfs storage nodes? I might buy a nas and install glusterfs onto it. I would be happy to listen to your recommendations for the server properties (for each clients and nodes) . I really dont know if I really need high amount of ram and good cpus to for the nodes. I am sure i need it for client servers. The files would be streamed as well, so the Automatic file replication is important, thus, my system should work like a cloud, when needed, according to high traffic, the storage nodes should copy the most demanded file to be streamed and would help me to get rid of scability problems and my visitors would able to stream/download those files. Also, i am open to your experiences/thoughts about any good solution. Luster, hdfs, rbdb are the other options and i would be happy to listen to your thoughts here. I would be very very happy to hear back from anyone commented of any words I have used here. Thanks

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Which is the fastest way to move 1Petabyte from one storage to a new one?

- by marc.riera

First of all, thanks for reading, and sorry for asking something related to my job. I understand that this is something that I should solve by myself but as you will see its something a bit difficult. A small description: Now Storage = 1PB using DDN S2A9900 storage for the OSTs, 4 OSS , 10 GigE network. (lustre 1.6) 100 compute nodes with 2x Infiniband 1 infiniband switch with 36 ports After Storage = Previous storage + another 1PB using DDN S2A 990 or LSI E5400 (still to decide) (lustre 2.0) 8 OSS , 10GigE network 100 compute nodes with 2x Infiniband Previous experience: transfered 120 TB in less than 3 days using following command: tar -C /old --record-size 2048 -b 2048 -cf - dir | tar -C /new --record-size 2048 -b 2048 -xvf - 2>&1 | tee /tmp/dir.log So , big problem here, using big mathematical equations I conclude that we are going to need 1 month to transfer the data from one side to the new one. During this time the researchers will need to step back, and I'm personally not happy with this. I'm telling you that we have infiniband connections because I think that may be there is a chance to use it to transfer the data using 18 compute nodes (18 * 2 IB = 36 ports) to transfer the data from one storage to the other. I'm trying to figure out if the IB switch will handle all the traffic but in case it just burn up will go faster than using 10GigE. Also, having lustre 1.6 and 2.0 agents on same server works quite well, with this there is no need to go by 1.8 to upgrade the metadata servers with two steps. Any ideas? Many thanks Note 1: Zoredache, we can divide it in two blocks (A)600Tb and (B)400Tb. The idea is to move (A) to new storage which is lustre2.0 formated, then format where (A) was with lustre2.0 and move (B) to this lustre2.0 block and extend with the space where (B) was. This way we will end with (A) and (B) on separate filesystems, with 1PB each.

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What are the typical methods used to scale up/out email storage servers?

- by nareshov

Hi, What I've tried: I have two email storage architectures. Old and new. Old: courier-imapds on several (18+) 1TB-storage servers. If one of them show signs of running out of disk space, we migrate a few email accounts to another server. the servers don't have replicas. no backups either. New: dovecot2 on a single huge server with 16TB (SATA) storage and a few SSDs we store fresh mails on the SSDs and run a doveadm purge to move mails older than a day to the SATA disks there is an identical server which has a max-15min-old rsync backup from the primary server higher-ups/management wanted to pack in as much storage as possible per server in order to minimise the cost of SSDs per server the rsync'ing is done because GlusterFS wasn't replicating well under that high small/random-IO. scaling out was expected to be done with provisioning another pair of such huge servers on facing disk-crunch issues like in the old architecture, manual moving of email accounts would be done. Concerns/doubts: I'm not convinced with the synchronously-replicated filesystem idea works well for heavy random/small-IO. GlusterFS isn't working for us yet, I'm not sure if there's another filesystem out there for this use case. The idea was to keep identical pairs and use DNS round-robin for email delivery and IMAP/POP3 access. And if one the servers went down for whatever reasons (planned/unplanned), we'd move the IP to the other server in the pair. In filesystems like Lustre, I get the advantage of a single namespace whereby I do not have to worry about manually migrating accounts around and updating MAILHOME paths and other metadata/data. Questions: What are the typical methods used to scale up/out with the traditional software (courier-imapd / dovecot)? Do traditional software that store on a locally mounted filesystem pose a roadblock to scale out with minimal "problems"? Does one have to re-write (parts of) these to work with an object-storage of some sort - such as OpenStack object storage?

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How to restore your production database without needing additional storage

- by David Atkinson

Production databases can get very large. This in itself is to be expected, but when a copy of the database is needed the database must be restored, requiring additional and costly storage. For example, if you want to give each developer a full copy of your production server, you'll need n times the storage cost for your n-developer team. The same is true for any test databases that are created during the course of your project lifecycle. If you've read my previous blog posts, you'll be aware that I've been focusing on the database continuous integration theme. In my CI setup I create a "production"-equivalent database directly from its source control representation, and use this to test my upgrade scripts. Despite this being a perfectly valid and practical thing to do as part of a CI setup, it's not the exact equivalent to running the upgrade script on a copy of the actual production database. So why shouldn't I instead simply restore the most recent production backup as part of my CI process? There are two reasons why this would be impractical. 1. My CI environment isn't an exact copy of my production environment. Indeed, this would be the case in a perfect world, and it is strongly recommended as a good practice if you follow Jez Humble and David Farley's "Continuous Delivery" teachings, but in practical terms this might not always be possible, especially where storage is concerned. It may just not be possible to restore a huge production database on the environment you've been allotted. 2. It's not just about the storage requirements, it's also the time it takes to do the restore. The whole point of continuous integration is that you are alerted as early as possible whether the build (yes, the database upgrade script counts!) is broken. If I have to run an hour-long restore each time I commit a change to source control I'm just not going to get the feedback quickly enough to react. So what's the solution? Red Gate has a technology, SQL Virtual Restore, that is able to restore a database without using up additional storage. Although this sounds too good to be true, the explanation is quite simple (although I'm sure the technical implementation details under the hood are quite complex!) Instead of restoring the backup in the conventional sense, SQL Virtual Restore will effectively mount the backup using its HyperBac technology. It creates a data and log file, .vmdf, and .vldf, that becomes the delta between the .bak file and the virtual database. This means that both read and write operations are permitted on a virtual database as from SQL Server's point of view it is no different from a conventional database. Instead of doubling the storage requirements upon a restore, there is no 'duplicate' storage requirements, other than the trivially small virtual log and data files (see illustration below). The benefit is magnified the more databases you mount to the same backup file. This technique could be used to provide a large development team a full development instance of a large production database. It is also incredibly easy to set up. Once SQL Virtual Restore is installed, you simply run a conventional RESTORE command to create the virtual database. This is what I have running as part of a nightly "release test" process triggered by my CI tool. RESTORE DATABASE WidgetProduction_virtual FROM DISK=N'C:\WidgetWF\ProdBackup\WidgetProduction.bak' WITH MOVE N'WidgetProduction' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_WidgetProduction_Virtual.vmdf', MOVE N'WidgetProduction_log' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_log_WidgetProduction_Virtual.vldf', NORECOVERY, STATS=1, REPLACE GO RESTORE DATABASE mydatabase WITH RECOVERY Note the only change from what you would do normally is the naming of the .vmdf and .vldf files. SQL Virtual Restore intercepts this by monitoring the extension and applies its magic, ensuring the 'virtual' restore happens rather than the conventional storage-heavy restore. My automated release test then applies the upgrade scripts to the virtual production database and runs some validation tests, giving me confidence that were I to run this on production for real, all would go smoothly. For illustration, here is my 8Gb production database: And its corresponding backup file: Here are the .vldf and .vmdf files, which represent the only additional used storage for the new database following the virtual restore. The beauty of this product is its simplicity. Once it is installed, the interaction with the backup and virtual database is exactly the same as before, as the clever stuff is being done at a lower level. SQL Virtual Restore can be downloaded as a fully functional 14-day trial. Technorati Tags: SQL Server

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How to restore your production database without needing additional storage

- by David Atkinson

Production databases can get very large. This in itself is to be expected, but when a copy of the database is needed the database must be restored, requiring additional and costly storage. For example, if you want to give each developer a full copy of your production server, you’ll need n times the storage cost for your n-developer team. The same is true for any test databases that are created during the course of your project lifecycle. If you’ve read my previous blog posts, you’ll be aware that I’ve been focusing on the database continuous integration theme. In my CI setup I create a “production”-equivalent database directly from its source control representation, and use this to test my upgrade scripts. Despite this being a perfectly valid and practical thing to do as part of a CI setup, it’s not the exact equivalent to running the upgrade script on a copy of the actual production database. So why shouldn’t I instead simply restore the most recent production backup as part of my CI process? There are two reasons why this would be impractical. 1. My CI environment isn’t an exact copy of my production environment. Indeed, this would be the case in a perfect world, and it is strongly recommended as a good practice if you follow Jez Humble and David Farley’s “Continuous Delivery” teachings, but in practical terms this might not always be possible, especially where storage is concerned. It may just not be possible to restore a huge production database on the environment you’ve been allotted. 2. It’s not just about the storage requirements, it’s also the time it takes to do the restore. The whole point of continuous integration is that you are alerted as early as possible whether the build (yes, the database upgrade script counts!) is broken. If I have to run an hour-long restore each time I commit a change to source control I’m just not going to get the feedback quickly enough to react. So what’s the solution? Red Gate has a technology, SQL Virtual Restore, that is able to restore a database without using up additional storage. Although this sounds too good to be true, the explanation is quite simple (although I’m sure the technical implementation details under the hood are quite complex!) Instead of restoring the backup in the conventional sense, SQL Virtual Restore will effectively mount the backup using its HyperBac technology. It creates a data and log file, .vmdf, and .vldf, that becomes the delta between the .bak file and the virtual database. This means that both read and write operations are permitted on a virtual database as from SQL Server’s point of view it is no different from a conventional database. Instead of doubling the storage requirements upon a restore, there is no ‘duplicate’ storage requirements, other than the trivially small virtual log and data files (see illustration below). The benefit is magnified the more databases you mount to the same backup file. This technique could be used to provide a large development team a full development instance of a large production database. It is also incredibly easy to set up. Once SQL Virtual Restore is installed, you simply run a conventional RESTORE command to create the virtual database. This is what I have running as part of a nightly “release test” process triggered by my CI tool. RESTORE DATABASE WidgetProduction_Virtual FROM DISK=N'D:\VirtualDatabase\WidgetProduction.bak' WITH MOVE N'WidgetProduction' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_WidgetProduction_Virtual.vmdf', MOVE N'WidgetProduction_log' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_log_WidgetProduction_Virtual.vldf', NORECOVERY, STATS=1, REPLACE GO RESTORE DATABASE WidgetProduction_Virtual WITH RECOVERY Note the only change from what you would do normally is the naming of the .vmdf and .vldf files. SQL Virtual Restore intercepts this by monitoring the extension and applies its magic, ensuring the ‘virtual’ restore happens rather than the conventional storage-heavy restore. My automated release test then applies the upgrade scripts to the virtual production database and runs some validation tests, giving me confidence that were I to run this on production for real, all would go smoothly. For illustration, here is my 8Gb production database: And its corresponding backup file: Here are the .vldf and .vmdf files, which represent the only additional used storage for the new database following the virtual restore. The beauty of this product is its simplicity. Once it is installed, the interaction with the backup and virtual database is exactly the same as before, as the clever stuff is being done at a lower level. SQL Virtual Restore can be downloaded as a fully functional 14-day trial. Technorati Tags: SQL Server

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How to restore your production database without needing additional storage

- by David Atkinson

Production databases can get very large. This in itself is to be expected, but when a copy of the database is needed the database must be restored, requiring additional and costly storage. For example, if you want to give each developer a full copy of your production server, you'll need n times the storage cost for your n-developer team. The same is true for any test databases that are created during the course of your project lifecycle. If you've read my previous blog posts, you'll be aware that I've been focusing on the database continuous integration theme. In my CI setup I create a "production"-equivalent database directly from its source control representation, and use this to test my upgrade scripts. Despite this being a perfectly valid and practical thing to do as part of a CI setup, it's not the exact equivalent to running the upgrade script on a copy of the actual production database. So why shouldn't I instead simply restore the most recent production backup as part of my CI process? There are two reasons why this would be impractical. 1. My CI environment isn't an exact copy of my production environment. Indeed, this would be the case in a perfect world, and it is strongly recommended as a good practice if you follow Jez Humble and David Farley's "Continuous Delivery" teachings, but in practical terms this might not always be possible, especially where storage is concerned. It may just not be possible to restore a huge production database on the environment you've been allotted. 2. It's not just about the storage requirements, it's also the time it takes to do the restore. The whole point of continuous integration is that you are alerted as early as possible whether the build (yes, the database upgrade script counts!) is broken. If I have to run an hour-long restore each time I commit a change to source control I'm just not going to get the feedback quickly enough to react. So what's the solution? Red Gate has a technology, SQL Virtual Restore, that is able to restore a database without using up additional storage. Although this sounds too good to be true, the explanation is quite simple (although I'm sure the technical implementation details under the hood are quite complex!) Instead of restoring the backup in the conventional sense, SQL Virtual Restore will effectively mount the backup using its HyperBac technology. It creates a data and log file, .vmdf, and .vldf, that becomes the delta between the .bak file and the virtual database. This means that both read and write operations are permitted on a virtual database as from SQL Server's point of view it is no different from a conventional database. Instead of doubling the storage requirements upon a restore, there is no 'duplicate' storage requirements, other than the trivially small virtual log and data files (see illustration below). The benefit is magnified the more databases you mount to the same backup file. This technique could be used to provide a large development team a full development instance of a large production database. It is also incredibly easy to set up. Once SQL Virtual Restore is installed, you simply run a conventional RESTORE command to create the virtual database. This is what I have running as part of a nightly "release test" process triggered by my CI tool. RESTORE DATABASE WidgetProduction_virtual FROM DISK=N'C:\WidgetWF\ProdBackup\WidgetProduction.bak' WITH MOVE N'WidgetProduction' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_WidgetProduction_Virtual.vmdf', MOVE N'WidgetProduction_log' TO N'C:\WidgetWF\ProdBackup\WidgetProduction_log_WidgetProduction_Virtual.vldf', NORECOVERY, STATS=1, REPLACE GO RESTORE DATABASE mydatabase WITH RECOVERY Note the only change from what you would do normally is the naming of the .vmdf and .vldf files. SQL Virtual Restore intercepts this by monitoring the extension and applies its magic, ensuring the 'virtual' restore happens rather than the conventional storage-heavy restore. My automated release test then applies the upgrade scripts to the virtual production database and runs some validation tests, giving me confidence that were I to run this on production for real, all would go smoothly. For illustration, here is my 8Gb production database: And its corresponding backup file: Here are the .vldf and .vmdf files, which represent the only additional used storage for the new database following the virtual restore. The beauty of this product is its simplicity. Once it is installed, the interaction with the backup and virtual database is exactly the same as before, as the clever stuff is being done at a lower level. SQL Virtual Restore can be downloaded as a fully functional 14-day trial. Technorati Tags: SQL Server

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Simple Scripting for your Exalogic Storage

- by Trond Strømme

As part of my job in Oracle ACS (Advanced Customer Services) I'm handling lots of different systems and customers. Among the recent systems I worked with have been Oracle's Exalogic engineered systems. One of the things I'd never had much exposure to as a system developer/architect/middleware guy/Java dude has been storage; outside of consuming it for my photography needs.. Well, I'm always ready for a new challenge... I'd downloaded the 7000 series storage simulator when it was released in the good old Sun days, found it fun and instructive to play around with, but as I never touched storage in any way (besides consuming it..) I forgot about it. A couple of years ago when I started working with Exalogic engineered systems it again came into light as an invaluable learning and testing tool for the embedded storage in an Exalogic; Oracle's Sun ZFS Storage 7320 Appliance. aaaanyway... I've been "booted" into a part-time role as the interim storage/system admin/middleware/Java guy for a client and found I needed to create the occasional report or summary or whatever.. of what's using the storage in the 7320 (as default configured for an Exalogic, 40T of disk in a mirrored configuration, yielding 18T of actual space.) Reading the nice documentation and some articles on the Oracle Technology Network I saw great possibilities with the embedded ECMAScript3/JavaScript engine in the 7000 series. In my personal opinion anyone who's dealing with Exalogic administration, or exposed to any of the 7000 series of storage appliances and servers that Oracle offers should have a VirtualBox instance of it kicking around. For development and testing it's a fantastic tool. (It can save you from explaining (most) of the embarrassing FAILS you can do if you test something in a production system to your management...) So download, and install. A small sidestep, if after firing up the 7000 series simulator in VirtualBox you've forgotten what it's IP address is, the following will sort you out if you log in directly via the running VirtualBox VM. So in my case I can ssh to 192.168.56.101 or point a browser to https://192.168.56.101:215 to log into the storage appliance. One simple way of executing a script on the 7320 is to ssh to the device and redirecting a file with the script in it to ssh. ssh [email protected] < myscript.js One question I got from my client and the people who will take over the systems was: "how can we see the quotas and allocations for all projects/shares in one easy go so we don't have to go navigating around in the BUI for all the hundreds of shares the 7320 is hosting just to check if anything is running dry?" Easy! JavaScript time, VirtualBox and emacs! //NOTE! this script is available 'as is' It has ben run on a couple of 7320's, (running 2010.08.17.3.0,1-1.25 & // 2011.04.24.1.0,1-1.8) a 7420 and the VB image, but I personally //offer no guarantee whatsoever that it won't make your server topple, catch fire or in any way go pear shaped.. //run at your own risk or learn from my code and or mistakes.. script run('cd /'); run('shares'); //get all projects: proj = list(); function spaceToGig(bytes){ return bytes/1073741824; //convert bytes to GB } function fullInPercent(quota, space_data){ tmp = (space_data/quota)*100; return tmp; } //print header, slightly good looking printf(" %s/%-15s %8s(GB) %7s(GB) %5s(GB) %7s(GB) %3s\n","Project", "Share","Quota","Ref", "Snap", "Total","%full"); printf("-------------------------------------------------------------------------------\n") //for each project, get all shares. check for quota and calculate percentage and human readable figures.. for (i=0;i<proj.length;i++){ run('select ' + proj[i]); //get all shares for a project var pshares = list(); //for each share get quota properties for (j=0;j<pshares.length;j++){ run('select ' + pshares[j]); quota = get('quota'); //properties associated with a share or inherited from a project spaceData = get('space_data'); spaceSnap = get('space_snapshots'); spaceTotal = get('space_total'); if(quota>0){ //has quota printf(" %s/%-15s \t%4.2fGB\t%.2fGB\t%.2fGB\t%.2fGB\t%5.2f%%\n",proj[i], pshares[j],spaceToGig(quota),spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),fullInPercent(quota,spaceTotal)); }else{ //no quota printf(" %s/%-15s \t%8s\t%.2fGB\t%.2fGB\t%.2fGB\t%s\n",proj[i],pshares[j], "N/A", spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),"N/A"); } run('cd ..'); } run('done'); } The resulting output should look something like this: Project/Share Quota(GB) Ref(GB) Snap(GB) Total(GB) %full ------------------------------------------------------------------------------- ACSExalogicSystem/domains N/A 0.04GB 0.00GB 0.04GB N/A ACSExalogicSystem/logs N/A 0.01GB 0.00GB 0.01GB N/A ACSExalogicSystem/nodemgrs N/A 0.00GB 0.00GB 0.00GB N/A ACSExalogicSystem/stores N/A 0.04GB 0.00GB 0.04GB N/A ***_dev/FMW_***_1 133GB 4.24GB 0.01GB 4.25GB 3.19% ***_dev/FMW_***_2 N/A 4.25GB 0.01GB 4.26GB N/A ***_dev/applications 10GB 0.00GB 0.00GB 0.00GB 0.00% ***_dev/domains 50GB 10.75GB 3.55GB 14.30GB 28.61% ***_dev/logs 20GB 0.32GB 0.01GB 0.33GB 1.66% ***_dev/softwaredepot 20GB 4.15GB 0.00GB 4.15GB 20.73% ***_dev/stores 20GB 0.01GB 0.00GB 0.01GB 0.05% ###_dev/FMW_###_1 400GB 17.63GB 0.12GB 17.75GB 4.44% ###_dev/applications N/A 0.00GB 0.00GB 0.00GB N/A ###_dev/domains 120GB 14.21GB 5.53GB 19.74GB 16.45% ###_dev/logs 15GB 0.00GB 0.00GB 0.00GB 0.00% ###_dev/softwaredepot 250GB 73.55GB 0.02GB 73.57GB 29.43% …snip My apologies if the output is a bit mis-aligned here and there, I only bothered making it look good, not perfect :/ I also removed some of the project names (*,#)

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WebLogic stuck thread protection

- by doublep

By default WebLogic kills stuck threads after 15 min (600 s), this is controlled by StuckThreadMaxTime parameter. However, I cannot find more details on how exactly "stuckness" is defined. Specifically: What is the point at which 15 min countdown begins. Request processing start? Last wait()-like method? Something else? Does this apply only to request-processing threads or to all threads? I.e. can a request-processing thread "escape" this protection by spawning a worker thread for a long task? Especially, can it delegate response writing to such a worker without 15 min countdown? My usecase is download of huge files through a permission system. Since a user needs to be authenticated and have permissions to view a file, I cannot (or at least don't know how) leave this to a simple HTTP server, e.g. Apache. And because files can be huge, download could (at least in theory) take more than 15 minutes.

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