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• Apache Webserver on Linux config - Can I create a Virtual Index.html

  - by yogione

  I have number of directories under Apache webserver on linux. I need a file - index.html in each directory. Can I keep a master index.html file in a specific location and tell apache to use this just incase there is no real index.html file in one of the sub directories ?

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• Connect to vmware virtual machine via network

  - by Arnis L.

  I want to connect to my vmware vm from home. To work network i'm connecting through VPN. VM sits on one of the workstations (can connect to it through RDC). Any tips how to do that? What software do i need (got VMWare workstation atm)? p.s. i'm quite a newbie at this.

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• Virtual bridge/switch for Windows server&client?

  - by Tiberiu-Ionu? Stan

  I can't find a very simple application, with litle to zero configuration on both client and server side which would help one computer to bring other computers on an existing private LAN. OpenVPN seems like an overkill for this type of thing, and is really hard to get running or debug by various clueless people trying to connect. Does such a software exist? It's very odd not to. THe Windows provided VPN (PPTP over TCP and GRE) is not what I'm looking for because it is often filtered by ISPs. Only TCP and UDP solutions pls. Encryption is not needed.

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• How to link specific ports to specific domains with Apache virtual hosts?

  - by theJoe

  We have a forward-facing linux box running Apache HTTP server that is acting as a reverse proxy for several back-end servers. The servers are accessed through specific domain names and ports and are set up as virtual hosts within Apache as such: Listen 8001 Listen 8002 <Virtualhost *:8001> ServerName service.one.mycompany.com ProxyPass / http://internal.one.mycompany.com:8001/ ProxyPassReverse / http://internal.one.mycompany.com:8001/ RewriteEngine On RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK) RewriteRule .* - [F] </Virtualhost> <Virtualhost *:8002> ServerName service.two.mycompany.com ProxyPass / http://internal.two.mycompany.com:8002/ ProxyPassReverse / http://internal.two.mycompany.com:8002/ RewriteEngine On RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK) RewriteRule .* - [F] </Virtualhost> The proxy server has only one IP address, and both domains are pointing to it. Accessing internal.one via service.one works fine, as does accessing internal.two via service.two. Now the problem is that Apache does not take the requesting domain into account when accessing the virtual hosts. What I mean is that both domains work for both ports: requests for service.one:8002 proxies to internal.two:8002, and requests for service.two:8001 proxies to internal.one:8001, where ideally both these requests should be denied. I can get around this by creating more virtual hosts that explicitly deny these requests: NameVirtualHost *:8001 NameVirtualHost *:8002 <Virtualhost *:8001> ServerName service.two.mycompany.com Redirect permanent / http://errorpage.mycompany.com/ </Virtualhost> <Virtualhost *:8002> ServerName service.one.mycompany.com Redirect permanent / http://errorpage.mycompany.com/ </Virtualhost> But this is not an ideal solution, since we plan to add more services to the proxy, and each new port would need to be explicitly denied on all the other domains, and each new domain would need to be explicitly denied on all ports it is not utilizing. As we add more services, the number of virtual hosts can get out of hand quickly. My question, then, is whether there is a better way? Can we explicitly tie specific ports to specific domains in a virtual host so that only that domain-port combination is processed, and all other combinations are not? Things I’ve tried: Adding NameVirtualHost *:8001, etc. without the additional virtual hosts. Setting ProxyRequests On and Off, as well as ProxyPreserveHost On and Off Adding the server name or IP address to the virtual host header, e.g. <VirtualHost service.one.mycompany.com:8001> Using the <proxy> directive inside the virtual host directive. Lots and lots of googling. The proxy server is running CentOS 6.2 64-bit, Apache HTTPD server 2.2.15. As mentioned, the proxy server has only one IP address, and all the domains we are using are pointing to it.

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• Virtual Subdomains

  - by Dave P

  I would like to manage subdomains exclusively through .htaccess. I am able to catch subdomains that I set up - for example, support.testsite.com - currently, I redirect that to testsite.com/support. What I would like to do is retain the subdomain, even after the redirect - so support.testsite.com seems to stay in the address bar for the user, even though it is actually located at testsite.com/support. Should I maintain another .htaccess file in /support that rewrites the address? Thanks!

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• SQLS Timeouts - High Reads in Profiler

  - by lb01

  Hi I've audited a SQLS2008 server with Profiler for one day.. the overhead didn't seem to trouble this new client my company has. They are using a legacy VB6 application as a front-end. They're experiencing timeouts once SQLS RAM usage is high. The server is currently running x64 sqls2008 on a VM with nearly 9 GB of RAM. SQL Server's 'max server memory option' is currently set to 6GB. I've put the results of the trace in a table and queried them using this query. SELECT TextData, ApplicationName, Reads FROM [TraceWednesday] WHERE textdata is not null and EventClass = 12 GROUP BY TextData, ApplicationName, Reads ORDER BY Reads DESC As I expected, some values are very high. Top Reads, in pages. 2504188 1965910 1445636 1252433 1239108 1210153 1088580 1072725 Am I correct in thinking that the top one (2504188 pages) is 20033504 KB, which then is roughly ~20'000 MB, 20GB? These queries are often executed and can take quite some time to run. Eventually RAM is used up because of the cache fattening, and timeouts occur once SQL cannot 'splash' pages in the buffer pool as much. Costs go up. Am I correct in my understanding? I've read that I should tune the associated T-SQL and create appropriate indices. Obviously cutting down the I/O would make SQL Server use less RAM. OR, maybe it might just slow down the process of chewing up the whole RAM. If a lot less pages are read, maybe it'll all run much better even when usage is high? (less time swapping, etc.) Currently, our only option is to restart SQL once a week when RAM usage is high, suddenly the timeouts disappear. SQL breathes again. I'm sure lots of DBAs have been in this situation.. I'm asking before I start digging out all of the bad T-SQL and put indices here and there, is there is something else I can do? Any advice except from what I know (not much yet..) Much appreciated. Leo.

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• How to use proxy on Virtual Box (Windows XP)

  - by John

  I'm not exactly the most tech savy so please bear with me. I am trying to connect through a proxy with my Virtualbox accounts. Initially I wanted to just set the browsers in each virtualbox under a proxy but my boss said that it can probably be done right off the bat under the virtualbox accounts itself. Could anyone guide me on how to do this? All the instructions online state that their should be a proxy setting in preferences however all I see is a Network Adapter tab. Thanks!

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• .htaccess - Simulating virtual host wrong link to Parent Directory in Directory Listing

  - by ?????? ?????

  I have a domain dedicated for my local server (.dev), and an .htaccess file which redirects requests like http://folder.dev/subfolder/ to /htdocs/folder/subfolder. It works great and all, except for one minor issue. When I have the Directory Listing enabled, I can access all the folders, subfolders and files properly, except when I click on the Parent Directory link, which, for example, should lead to http://folder.dev, but redirects to http://folder.dev/folder/ and consequently throws 404 not found. Similarly, if Parent Directory should link to http://folder.dev/subfolder/, it links to http://folder.dev/folder/subfolder/. Here's how my .htaccess looks like: RewriteEngine On RewriteBase / RewriteCond %{REQUEST_URI} !(/$|\.) RewriteRule (.*) %{REQUEST_URI}/ [R=301,L] RewriteCond %{ENV:REDIRECT_SUBDOMAIN} ="" RewriteCond %{HTTP_HOST} ^(www\.)?([a-z0-9][-a-z0-9]+)\.dev\.?(:80)?$ [NC] RewriteCond %2 !^www|ftp|mail|pop3|localhost$ RewriteCond %{DOCUMENT_ROOT}/%2 -d RewriteRule ^(.*) %2/$1 [E=SUBDOMAIN:%2,L] RewriteRule ^ - [E=SUBDOMAIN:%{ENV:REDIRECT_SUBDOMAIN}] Apart from that one thing, everything else works fine (e.g. relative links in documents etc.)

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• DCHP enabled on router and on my virtual server

  - by SantaC

  I am wondering if there is any problem using dhcp on my router as well on my VM server 2008R2 machine. Can any interference occur?

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• Cannot SSH into Virtual Machine

  - by MasterGberry

  I am running a CentOS VM on my desktop that I use for development testing when coding in python. At my school I have a dedicated IP setup for the VM and my desktop so I never seem to have an issue ssh'ing from desktop into VM. I am now at home for winter break and cannot seem to SSH into the VM using the local ip address behind my router, the external IP with port 22 forwarded to my VM, or anything. Strangely enough I can ssh into my production server and then fromt here ssh into the VM, but not from my desktop to the VM directly What should I do to get this to work? Thanks

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• Storage sizing for virtual machines

  - by njo

  I am currently doing research to determine the consolidation ratio my company could expect should we start using a virtualization platform. I find myself continually running into a dead end when researching how to translate observed performance (weeks of perfmon data) to hdd array requirements for a virtualization server. I am familiar with the concept of IOPs, but they seem to be an overly simplistic measurement that fails to take into account cache, write combining, etc. Is there a seminal work on storage array performance analysis that I'm missing? This seems like an area where hearsay and 'black magic' have taken over for cold, hard fact.

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• To Run Linux (Ubuntu) on Windows 7, is using Virtual PC one of the best ways?

  - by Jian Lin

  I need to try Linux (Ubuntu) and feel hesitant to install Ubuntu on top of a Win 7 machine to dual boot (might need to use Win7 and Ubuntu at the same time). Is creating a Virtual PC on Win7, and then install the latest Ubuntu on that Virtual PC one of the better option? So I think I can create a Virtual PC with an empty virtual hard disk (vhd), say, for 30GB, and then put in the Ubuntu DVD-R or CD-R to install Ubuntu onto that empty hard disk.

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• Turning a (dual boot) Ubuntu 9 into a virtual machine

  - by xain

  I have a dual boot box (Ubuntu 9 and Vista) and I'm about to upgrade Vista to Win 7. Being Ubuntu my main development environment, I'd like to use it as it is from the new environment via VirtualBox or VMWare. I know tools like clonezilla that backup entire drives; in my case, the linux partitions are distributed between several disks which in turn contain both linux and windows data. My intention is to use some backup tool (like Clonezilla if it fits) that allows me to ONLY backup the linux partitions distributed in several disks. Any hints ? Thanks in advance.

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• Ubuntu 9.10 Server (minimal virtual machine) partitioning

  - by John

  I am setting up a generic Ubuntu server and am trying to figure out the (best) way to partition the machine. Again, this is just a generic one: The default drive is 20GB. Some guides show: Separate /home, /usr, /var and /tmp partitions Another one suggested something like this: / 4GB /boot 512MB /tmp 1GB /home 5GB /usr 5GB /var 5GB What is the best way to accomplish this?

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• Dynamic Virtual Hosts In Apache with www and non-www subdomains

  - by haukish

  I don't know apache very well and I've got a problem with configure mod_vhost_alias This is my httpd.conf file: UseCanonicalName Off LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon <Directory /var/www/sites/> Options FollowSymLinks AllowOverride All </Directory> <VirtualHost *:80> CustomLog logs/access_log.sites vcommon ServerAlias *.domain.com UseCanonicalName Off VirtualDocumentRoot /var/www/sites/%1/ </VirtualHost> Subdomains work fine without www. but I need to make them work with www too. Here's an example: something.domain.com - site is loading www.something.domain.com - Not Found What should I do?

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• Phone solution for virtual company

  - by EJB

  I am looking for recommendations/links for a service that can give/assign me a phone number, have a recorded messages played when someone calls such as "press 1 for ..., press 2 for yyy etc" and then allow the caller to leave a message that is then emailed to the owner of the particular voicemail box. Google voice works for 1 mailbox only, but something like that with multiple mailboxes and multiple email addresses would be great.

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• The instruction at “0x7c910a19” referenced memory at “oxffffffff”. The memory could not be “read”

  - by ClareBear

  Hello guys/girls I have a small issue, I receive the following error before the .vbs terminates. I don't know why this error is thrown. Below is the process of the .vbs file: Call ImportTransactions() Call UpdateTransactions() Function ImportTransactions() Dim objConnection, objCommand, objRecordset, strOracle Dim strSQL, objRecordsetInsert Set objConnection = CreateObject("ADODB.Connection") objConnection.Open "DSN=*****;UID=*****;PWD==*****;" Set objCommand = CreateObject("ADODB.Command") Set objRecordset = CreateObject("ADODB.Recordset") strOracle = "SELECT query here from Oracle database" objCommand.CommandText = strOracle objCommand.CommandType = 1 objCommand.CommandTimeout = 0 Set objCommand.ActiveConnection = objConnection objRecordset.cursorType = 0 objRecordset.cursorlocation = 3 objRecordset.Open objCommand, , 1, 3 If objRecordset.EOF = False Then Do Until objRecordset.EOF = True strSQL = "INSERT query here into SQL database" strSQL = Query(strSQL) Call RunSQL(strSQL, objRecordsetInsert, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) objRecordset.MoveNext Loop End If objRecordset.Close() Set objRecordset = Nothing Set objRecordsetInsert = Nothing End Function Function UpdateTransactions() Dim strSQLUpdateVAT, strSQLUpdateCodes Dim objRecordsetVAT, objRecordsetUpdateCodes strSQLUpdateVAT = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1)" Call RunSQL(strSQLUpdateVAT, objRecordsetVAT, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) strSQLUpdateCodes = "UPDATE query here SET [value:costing output] = ([value:costing output] * -1) different WHERE clause" Call RunSQL(strSQLUpdateCodes, objRecordsetUpdateCodes, False, conTimeOut, conServer, conDatabase, conUsername, conPassword) Set objRecordsetVAT = Nothing Set objRecordsetUpdateCodes = Nothing End Function It does both the import and update and seems to throw this error after. If I comment out the ImportTransactions it doesnt throw a error, however I have produced similar code for another vbs file and this does not throw any errors Thanks in advance for any help, Clare

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• VMWare server: virtual machine start-up reaches 95% and hangs

  - by Magsol

  This problem cropped up today, after updating my eVGA motherboard's chipset in order to try and fix an unrelated issue. After installing the chipset update (contained SATA and Ethernet drivers), every time I've tried to start my Ubuntu VM, it reaches 95% in the web interface and then just hangs. I'm using VMWare Server 2.0.2, running it within Windows 7 64-bit. I haven't had any issues up until now, and I suspect it has something to do with the chipset update. I've already tried reinstalling VMWare itself, removing the VM from the inventory and re-adding it, and neither has proved successful. I'm also not sure how to kill the VMware server process itself once the start-up hangs; I've only been able to try again by rebooting (as none of the VMWare Services listed kill the server process itself). Any insights? Edit: Uhhh...as an addendum: I have a cron job set up on my Ubuntu VM that runs every 20 minutes. The VM is still listed in the VMWare web interface as at 95% of startup, and the start/stop buttons are still disabled, but the cronjob just ran. I also tested SSH, and I was able to tunnel into the Ubuntu VM as well. Now I'm really confused. Edit #2: I just started a thread on the VMWare Server support forums on this same topic. Hopefully between the two communities, we can come up with an answer: http://communities.vmware.com/thread/251033 Edit #3: In lieu of a specific fix, I've switched over to VirtualBox, and all is working just fine.

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• Trouble on setting SSL certificates for Virtual Hosts using Apache\Phusion Passenger in localhost

  - by user502052

  I am using Ruby on Rails 3 and I would like to make to work HTTPS connections on localhost. I am using: Apache v2 + Phusion Passenger Mac OS + Snow Leopard v10.6.6 My Ruby on Rails installation use the Typhoeus gem (it is possible to use the Ruby net\http library but the result doesn't change) to make HTTP requests over HTTPS. I created self-signed ca.key, pjtname.crt and pjtname.key as detailed on the Apple website. Notice: Following instruction from the Apple website, on running the openssl req -new -key server.key -out server.csr command (see the link) at this point Common Name (eg, YOUR name) []: (this is the important one) I entered *pjtname.com so that is valid for all sub_domain of that site. In my Apache httpd.conf I have two virtual hosts configured in this way: # Secure (SSL/TLS) connections #Include /private/etc/apache2/extra/httpd-ssl.conf # # Note: The following must must be present to support # starting without SSL on platforms with no /dev/random equivalent # but a statically compiled-in mod_ssl. # <IfModule ssl_module> SSLRandomSeed startup builtin SSLRandomSeed connect builtin </IfModule> Include /private/etc/apache2/other/*.conf # Passenger configuration LoadModule passenger_module /Users/<my_user_name>/.rvm/gems/ruby-1.9.2-p136/gems/passenger-3.0.2/ext/apache2/mod_passenger.so PassengerRoot /Users/<my_user_name>/.rvm/gems/ruby-1.9.2-p136/gems/passenger-3.0.2 PassengerRuby /Users/<my_user_name>/.rvm/wrappers/ruby-1.9.2-p136/ruby # Go ahead and accept connections for these vhosts # from non-SNI clients SSLStrictSNIVHostCheck off # Ensure that Apache listens on port 443 Listen 443 # Listen for virtual host requests on all IP addresses NameVirtualHost *:80 NameVirtualHost *:443 # # PJTNAME.COM and subdomains SETTING # <VirtualHost *:443> # Because this virtual host is defined first, it will # be used as the default if the hostname is not received # in the SSL handshake, e.g. if the browser doesn't support # SNI. ServerName pjtname.com:443 DocumentRoot "/Users/<my_user_name>/Sites/pjtname.com/pjtname.com/public" ServerAdmin [email protected] ErrorLog "/private/var/log/apache2/error_log" TransferLog "/private/var/log/apache2/access_log" RackEnv development <Directory "/Users/<my_user_name>/Sites/pjtname.com/pjtname.com/public"> Order allow,deny Allow from all </Directory> # SSL Configuration SSLEngine on # Self Signed certificates # Server Certificate SSLCertificateFile /private/etc/apache2/ssl/wildcard.certificate/pjtname.crt # Server Private Key SSLCertificateKeyFile /private/etc/apache2/ssl/wildcard.certificate/pjtname.key # Server Intermediate Bundle SSLCertificateChainFile /private/etc/apache2/ssl/wildcard.certificate/ca.crt </VirtualHost> # HTTP Setting <VirtualHost *:80> ServerName pjtname.com DocumentRoot "/Users/<my_user_name>/Sites/pjtname.com/pjtname.com/public" RackEnv development <Directory "/Users/<my_user_name>/Sites/pjtname.com/pjtname.com/public"> Order allow,deny Allow from all </Directory> </VirtualHost> <VirtualHost *:443> ServerName users.pjtname.com:443 DocumentRoot "/Users/<my_user_name>/Sites/pjtname.com/users.pjtname.com/public" ServerAdmin [email protected] ErrorLog "/private/var/log/apache2/error_log" TransferLog "/private/var/log/apache2/access_log" RackEnv development <Directory "/Users/<my_user_name>/Sites/pjtname.com/users.pjtname.com/public"> Order allow,deny Allow from all </Directory> # SSL Configuration SSLEngine on # Self Signed certificates # Server Certificate SSLCertificateFile /private/etc/apache2/ssl/wildcard.certificate/pjtname.crt # Server Private Key SSLCertificateKeyFile /private/etc/apache2/ssl/wildcard.certificate/pjtname.key # Server Intermediate Bundle SSLCertificateChainFile /private/etc/apache2/ssl/wildcard.certificate/ca.crt </VirtualHost> # HTTP Setting <VirtualHost *:80> ServerName users.pjtname.com DocumentRoot "/Users/<my_user_name>/Sites/pjtname.com/users.pjtname.com/public" RackEnv development <Directory "/Users/<my_user_name>/Sites/pjtname.com/users.pjtname.com/public"> Order allow,deny Allow from all </Directory> </VirtualHost> In the host file I have: ## # Host Database # # localhost is used to configure the loopback interface # when the system is booting. Do not change this entry. ## 127.0.0.1 localhost 255.255.255.255 broadcasthost ::1 localhost fe80::1%lo0 localhost # PJTNAME.COM SETTING 127.0.0.1 pjtname.com 127.0.0.1 users.pjtname.com All seems to work properly because I have already set everything (I think correctly): I generated a wildcard certificate for my domains and sub-domains (in this example: *.pjtname.com) I have set base-named virtualhosts in the http.conf file listening on port :433 and :80 My browser accept certificates also if it alerts me that those aren't safe (notice: I must accept certificates for each domain\sub-domain; that is, [only] at the first time I access a domain or sub-domain over HTTPS I must do the same procedure for acceptance) and I can have access to pages using HTTPS After all this work, when I make a request using Typhoeus (I can use also the Ruby Net::Http library and the result doesn't change) from the pjtname.com RoR application: # Typhoeus request Typhoeus::Request.get("https://users.pjtname.com/") I get something like a warning about the certificate: --- &id001 !ruby/object:Typhoeus::Response app_connect_time: 0.0 body: "" code: 0 connect_time: 0.000625 # Here is the warning curl_error_message: Peer certificate cannot be authenticated with known CA certificates curl_return_code: 60 effective_url: https://users.pjtname.com/ headers: "" http_version: mock: false name_lookup_time: 0.000513 pretransfer_time: 0.0 request: !ruby/object:Typhoeus::Request after_complete: auth_method: body: ... All this means that something is wrong. So, what I have to do to avoid the "Peer certificate cannot be authenticated with known CA certificates" warning and make the HTTPS request to work? Where is\are the error\errors (I think in the Apache configuration, but where?!)? P.S.: if you need some more info, let me know.

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• In Ruby, how to I read memory values from an external process?

  - by grg-n-sox

  So all I simply want to do is make a Ruby program that reads some values from known memory address in another process's virtual memory. Through my research and basic knowledge of hex editing a running process's x86 assembly in memory, I have found the base address and offsets for the values in memory I want. I do not want to change them; I just want to read them. I asked a developer of a memory editor how to approach this abstract of language and assuming a Windows platform. He told me the Win32API calls for OpenProcess, CreateProcess, ReadProcessMemory, and WriteProcessMemory were the way to go using either C or C++. I think that the way to go would be just using the Win32API class and mapping two instances of it; One for either OpenProcess or CreateProcess, depending on if the user already has th process running or not, and another instance will be mapped to ReadProcessMemory. I probably still need to find the function for getting the list of running processes so I know which running process is the one I want if it is running already. This would take some work to put all together, but I am figuring it wouldn't be too bad to code up. It is just a new area of programming for me since I have never worked this low level from a high level language (well, higher level than C anyways). I am just wondering of the ways to approach this. I could just use a bunch or Win32API calls, but that means having to deal with a bunch of string and array pack and unpacking that is system dependant I want to eventually make this work cross-platform since the process I am reading from is produced from an executable that has multiple platform builds, (I know the memory address changes from system to system. The idea is to have a flat file that contains all memory mappings so the Ruby program can just match the current platform environment to the matching memory mapping.) but from the looks of things I'll just have to make a class that wraps whatever is the current platform's system shared library memory related function calls. For all I know, there could already exist a Ruby gem that takes care of all of this for me that I am just not finding. I could also possibly try editing the executables for each build to make it so whenever the memory values I want to read from are written to by the process, it also writes a copy of the new value to a space in shared memory that I somehow have Ruby make an instance of a class that is a pointer under the hood to that shared memory address and somehow signal to the Ruby program that the value was updated and should be reloaded. Basically a interrupt based system would be nice, but since the purpose of reading these values is just to send to a scoreboard broadcasted from a central server, I could just stick to a polling based system that sends updates at fixed time intervals. I also could just abandon Ruby altogether and go for C or C++ but I do not know those nearly as well. I actually know more x86 than C++ and I only know C as far as system independent ANSI C and have never dealt with shared system libraries before. So is there a gem or lesser known module available that has already done this? If not, then any additional information as to how to accomplish this would be nice. I guess, long story short, how do I do all this? Thanks in advance, Grg PS: Also a confirmation that those Win32API calls should be aimed at the kernel32.dll library would be nice.

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• .NET 3.5SP1 64-bit memory model vs. 32-bit memory model

  - by James Dunne

  As I understand it, the .NET memory model on a 32-bit machine guarantees 32-bit word writes and reads to be atomic operations but does not provide this guarantee on 64-bit words. I have written a quick tool to demonstrate this effect on a Windows XP 32-bit OS and am getting results consistent with that memory model description. However, I have taken this same tool's executable and run it on a Windows 7 Enterprise 64-bit OS and am getting wildly different results. Both the machines are identical specs just with different OSes installed. I would have expected that the .NET memory model would guarantee writes and reads to BOTH 32-bit and 64-bit words to be atomic on a 64-bit OS. I find results completely contrary to BOTH assumptions. 32-bit reads and writes are not demonstrated to be atomic on this OS. Can someone explain to me why this fails on a 64-bit OS? Tool code: using System; using System.Threading; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { var th = new Thread(new ThreadStart(RunThread)); var th2 = new Thread(new ThreadStart(RunThread)); int lastRecordedInt = 0; long lastRecordedLong = 0L; th.Start(); th2.Start(); while (!done) { int newIntValue = intValue; long newLongValue = longValue; if (lastRecordedInt > newIntValue) Console.WriteLine("BING(int)! {0} > {1}, {2}", lastRecordedInt, newIntValue, (lastRecordedInt - newIntValue)); if (lastRecordedLong > newLongValue) Console.WriteLine("BING(long)! {0} > {1}, {2}", lastRecordedLong, newLongValue, (lastRecordedLong - newLongValue)); lastRecordedInt = newIntValue; lastRecordedLong = newLongValue; } th.Join(); th2.Join(); Console.WriteLine("{0} =? {2}, {1} =? {3}", intValue, longValue, Int32.MaxValue / 2, (long)Int32.MaxValue + (Int32.MaxValue / 2)); } private static long longValue = Int32.MaxValue; private static int intValue; private static bool done = false; static void RunThread() { for (int i = 0; i < Int32.MaxValue / 4; ++i) { ++longValue; ++intValue; } done = true; } } } Results on Windows XP 32-bit: Windows XP 32-bit Intel Core2 Duo P8700 @ 2.53GHz BING(long)! 2161093208 > 2161092246, 962 BING(long)! 2162448397 > 2161273312, 1175085 BING(long)! 2270110050 > 2270109040, 1010 BING(long)! 2270115061 > 2270110059, 5002 BING(long)! 2558052223 > 2557528157, 524066 BING(long)! 2571660540 > 2571659563, 977 BING(long)! 2646433569 > 2646432557, 1012 BING(long)! 2660841714 > 2660840732, 982 BING(long)! 2661795522 > 2660841715, 953807 BING(long)! 2712855281 > 2712854239, 1042 BING(long)! 2737627472 > 2735210929, 2416543 1025780885 =? 1073741823, 3168207035 =? 3221225470 Notice how BING(int) is never written and demonstrates that 32-bit reads/writes are atomic on this 32-bit OS. Results on Windows 7 Enterprise 64-bit: Windows 7 Enterprise 64-bit Intel Core2 Duo P8700 @ 2.53GHz BING(long)! 2208482159 > 2208121217, 360942 BING(int)! 280292777 > 279704627, 588150 BING(int)! 308158865 > 308131694, 27171 BING(long)! 2549116628 > 2548884894, 231734 BING(int)! 534815527 > 534708027, 107500 BING(int)! 545113548 > 544270063, 843485 BING(long)! 2710030799 > 2709941968, 88831 BING(int)! 668662394 > 667539649, 1122745 1006355562 =? 1073741823, 3154727581 =? 3221225470 Notice that BING(long) AND BING(int) are both displayed! Why are the 32-bit operations failing, let alone the 64-bit ones?

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• OBI already has a caching mechanism in presentation layer and BI server layer. How is the new in-memory caching better for performance?

  - by Varun

  Question: OBI already has a caching mechanism in presentation layer and BI server layer. How is the new in-memory caching better for performance? Answer: OBI Caching only speeds up what has been seen before. An In-memory data structure generated by the summary advisor is optimized to provide maximum value by accounting for the expected broad usage and drilldowns. It is possible to adapt the in-memory data to seasonality by running the summary advisor on specific workloads. Moreover, the in-memory data is created in an analytic database providing maximum performance for the large amount of memory available.

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• How can I determine which GPU card is running at PCI Express 2.0 x16 & which is using x8?

  - by M. Tibbits

  Is there a way to determine the speed of the PCI Express connection to a specific card? I have three cards plugged in: two Nvidia GTX 480's (one at x16 & and one at x8) one Nvidia GTX 460 running at x8 Is there some way, either by a function call in C or an option to lspci that I can determine the bus speed of the graphics cards? When I only use one of the cards for my CUDA program, I'd like to use the one which is running at x16. Thanks! Note: lspci -vvv dumps out For the two GTX 480s. I don't see any differences that pertain to bus speed. 03:00.0 VGA compatible controller: nVidia Corporation Device 06c0 (rev a3) Subsystem: eVga.com. Corp. Device 1480 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 16 Region 0: Memory at d4000000 (32-bit, non-prefetchable) [size=32M] Region 1: Memory at b0000000 (64-bit, prefetchable) [size=128M] Region 3: Memory at bc000000 (64-bit, prefetchable) [size=64M] Region 5: I/O ports at df00 [disabled] [size=128] [virtual] Expansion ROM at b8000000 [disabled] [size=512K] Capabilities: <access denied> Kernel driver in use: nvidia Kernel modules: nvidia, nvidiafb, nouveau 03:00.1 Audio device: nVidia Corporation Device 0be5 (rev a1) Subsystem: eVga.com. Corp. Device 1480 Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Interrupt: pin B routed to IRQ 5 Region 0: [virtual] Memory at d7ffc000 (32-bit, non-prefetchable) [disabled] [size=16K] Capabilities: <access denied> 04:00.0 VGA compatible controller: nVidia Corporation Device 06c0 (rev a3) Subsystem: eVga.com. Corp. Device 1480 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 16 Region 0: Memory at dc000000 (32-bit, non-prefetchable) [size=32M] Region 1: Memory at c0000000 (64-bit, prefetchable) [size=128M] Region 3: Memory at cc000000 (64-bit, prefetchable) [size=64M] Region 5: I/O ports at cf00 [size=128] [virtual] Expansion ROM at c8000000 [disabled] [size=512K] Capabilities: <access denied> Kernel driver in use: nvidia Kernel modules: nvidia, nvidiafb, nouveau 04:00.1 Audio device: nVidia Corporation Device 0be5 (rev a1) Subsystem: eVga.com. Corp. Device 1480 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0, Cache Line Size: 64 bytes Interrupt: pin B routed to IRQ 5 Region 0: Memory at dfffc000 (32-bit, non-prefetchable) [size=16K] Capabilities: <access denied> And the only differences I see relate specifically to the memory mapping: myComputer:~> diff card1 card2 3c3 < Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- --- > Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- 7,11c7,11 < Region 0: Memory at d4000000 (32-bit, non-prefetchable) [size=32M] < Region 1: Memory at b0000000 (64-bit, prefetchable) [size=128M] < Region 3: Memory at bc000000 (64-bit, prefetchable) [size=64M] < Region 5: I/O ports at df00 [disabled] [size=128] < [virtual] Expansion ROM at b8000000 [disabled] [size=512K] --- > Region 0: Memory at dc000000 (32-bit, non-prefetchable) [size=32M] > Region 1: Memory at c0000000 (64-bit, prefetchable) [size=128M] > Region 3: Memory at cc000000 (64-bit, prefetchable) [size=64M] > Region 5: I/O ports at cf00 [size=128] > [virtual] Expansion ROM at c8000000 [disabled] [size=512K] 18c18 < Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- --- > Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- 19a20 > Latency: 0, Cache Line Size: 64 bytes 21c22 < Region 0: [virtual] Memory at d7ffc000 (32-bit, non-prefetchable) [disabled] [size=16K] --- > Region 0: Memory at dfffc000 (32-bit, non-prefetchable) [size=16K]

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• Caching by in-memory dictionaries. Are we doing it all wrong?

  - by user73983

  This approach is pretty much the accepted way to do anything in our company. A simple example : when a piece of data for a customer is requested from a service, we fetch all the data for that customer(relevant part to the service) and save it in a in-memory dictionary then serve it from there on following requests(we run singleton services). Any update goes to DB, then updates the in memory dictionary. It seems all simple and harmless but as we implement more complicated business rules the cache gets out of sync and we have to deal with hard to find bugs. Sometimes we defer writing to database, keeping new data in cache till then. There are cases when we store millions of rows in memory because the table has many relations to other tables and we need to show aggregate data quickly. All this cache handling is a big part of our codebase and I sense this is not the right way to do it. All of this juggling adds too much noise to the code and it makes it hard to understand the actual business logic. However I don't think we can serve data in a reasonable amount of time if we have to hit the database every time. I am unhappy about the current situation but I don't have a better alternative. My only solution would be to use NHibernate 2nd level cache but I have nearly no experience with it. I know many campanies use Redis or MemCached heavily to gain performance but I have no idea how I would integrate them into our system. I also don't know if they can perform better than in-memory data structures and queries. Are there any alternative approaches that I should look into?

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• GNU/Linux swapping blocks system

  - by Ole Tange

  I have used GNU/Linux on systems from 4 MB RAM to 512 GB RAM. When they start swapping, most of the time you can still log in and kill off the offending process - you just have to be 100-1000 times more patient. On my new 32 GB system that has changed: It blocks when it starts swapping. Sometimes with full disk activity but other times with no disk activity. To examine what might be the issue I have written this program. The idea is: 1 grab 3% of the memory free right now 2 if that caused swap to increase: stop 3 keep the chunk used for 30 seconds by forking off 4 goto 1 - #!/usr/bin/perl sub freekb { my $free = `free|grep buffers/cache`; my @a=split / +/,$free; return $a[3]; } sub swapkb { my $swap = `free|grep Swap:`; my @a=split / +/,$swap; return $a[2]; } my $swap = swapkb(); my $lastswap = $swap; my $free; while($lastswap >= $swap) { print "$swap $free"; $lastswap = $swap; $swap = swapkb(); $free = freekb(); my $used_mem = "x"x(1024 * $free * 0.03); if(not fork()) { sleep 30; exit(); } } print "Swap increased $swap $lastswap\n"; Running the program forever ought to keep the system at the limit of swapping, but only grabbing a minimal amount of swap and do that very slowly (i.e. a few MB at a time at most). If I run: forever free | stdbuf -o0 timestamp > freelog I ought to see swap slowly rising every second. (forever and timestamp from https://github.com/ole-tange/tangetools). But that is not the behaviour I see: I see swap increasing in jumps and that the system is completely blocked during these jumps. Here the system is blocked for 30 seconds with the swap usage increases with 1 GB: secs 169.527 Swap: 18440184 154184 18286000 170.531 Swap: 18440184 154184 18286000 200.630 Swap: 18440184 1134240 17305944 210.259 Swap: 18440184 1076228 17363956 Blocked: 21 secs. Swap increase 2400 MB: 307.773 Swap: 18440184 581324 17858860 308.799 Swap: 18440184 597676 17842508 330.103 Swap: 18440184 2503020 15937164 331.106 Swap: 18440184 2502936 15937248 Blocked: 20 secs. Swap increase 2200 MB: 751.283 Swap: 18440184 885288 17554896 752.286 Swap: 18440184 911676 17528508 772.331 Swap: 18440184 3193532 15246652 773.333 Swap: 18440184 1404540 17035644 Blocked: 37 secs. Swap increase 2400 MB: 904.068 Swap: 18440184 613108 17827076 905.072 Swap: 18440184 610368 17829816 942.424 Swap: 18440184 3014668 15425516 942.610 Swap: 18440184 2073580 16366604 This is bad enough, but what is even worse is that the system sometimes stops responding at all - even if I wait for hours. I have the feeling it is related to the swapping issue, but I cannot tell for sure. My first idea was to tweak /proc/sys/vm/swappiness from 60 to 0 or 100, just to see if that had any effect at all. 0 did not have an effect, but 100 did cause the problem to arise less often. How can I prevent the system from blocking for such a long time? Why does it decide to swapout 1-3 GB when less than 10 MB would suffice?

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