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  • yum update with shared cache

    - by Sammitch
    We've got a big batch of RHEL6 machines that are due for patching, and for some reason the process here does not involve a local repo. I'm new here, I've asked why, ["it just didn't work"] and I don't have enough time to make it work before the window that's already scheduled. So the usual method is to install yum-downloadonly and run yum update --downloadonly --downloaddir=/mnt/cifs_share and then yum update /mnt/cifs_share/*.rpm which just does not look right to me since not all of these machines have the same set of installed packages. The method I tried today was mounting the share to /var/cache/yum/x86_64/6Server/rhel-x86_64-server-6/packages/ which worked, but then yum automatically deleted everything once it finished. I've looked over the yum man page, but I don't see any flag I can feed it to stop it from deleting everything, nor a flag like up2date's --tmpdir=/mnt/cifs_share. Can anyone out there help me kludge this together until I can get a local repository working?

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  • System Lags/Freezes when under high usgage

    - by tom
    I am not sure if its my GPU / Memory or Hard drive thats failing. For example if I'm runnning more than one instance of chrome and running an application that takes up a lot of resources, my system will start to lag and freeze. When I launch Photoshop the GPU feature disables automatically, this also lags when I click on menus and when working on documents in Photoshop. I really dont know where to start, if i should buy a new graphics card or test the memory or could it be my OS drive? System: Windows 7 64bit, ATI Raedeon 5850, Corsair 2x4GB http://i.stack.imgur.com/qqkLZ.jpg

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  • How to get the spec of a machine on Linux?

    - by machinePurchaser
    I am interested in getting the spec of a machine, because I am thinking getting a similar server. What I am mostly interested in knowing is the number of cores / CPUs / etc., the amount of memory, the speed of the CPUs, the CPU cache size, and any other detail which is important for performance. My question is two-fold: Which parameters should I be interested in other than the ones I specified above? Is there an easy way to read them off the machine in Linux? cat /proc/cpuinfo reveals a lot about the CPUs, for example... What about memory (would rather not rely on top), etc?

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  • Setup shared internet connection on virtualbox with fixed IP

    - by Tom
    I am a web developer and until recently I have been using ubuntu as my OS. For many reasons, I have switched back to windows. I still want to keep my server on linux platform, so I setup my local server as a virtual machine. Everything works great, but i have a little struggle with the networking. Since I am working in different places and going around clients, I connect to all sorts of network with different settings. That means the possible IP range is very dynamic which causes issues when I work on my local server. At the moment I have a dynamic IP on my host and static IP on my guest. That way I can access the server from my host (by adding record to hosts file). I also have internet connection on the guest. But once i change networks, it does not work (assuming the network has different configuration). My question is, how to setup host-guest networking, so no matter what network I connect to, I can keep my static IP on guest, which is registered in hosts file on my host so I can access the webserver and also I will have internet connection on the guest? Hope it make sense. Thank you

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  • Have a set a cgi scripts shared by multiple domains

    - by rpat
    Goal: Have multiple domains share a set of cgi(perl) scripts Environment: Apache 2.0 on a dedicated Cent OS server. (Apache configuration files generated by cPanel) I have dozens of domains on the dedicated server. The domains set up by cPanel under VirtualHost section. I have almost no knowledge of Apache. Most of what I do is taken care of by cPanel. I would like to put a set of scripts under one directory (perhaps under / or /opt ) and for each of the domains, under the individual cgi-bin, I would like to create a symbolic link to this common directory. This way I am hoping to avoid having to keep a copy of scripts for every domain. Since Apache config files are generated by cPanel, I would not like to manually make changes to those. Beside, I could mess things up. I see that cPanel recommends use of include files rather than changing the httpd.conf Perhaps I need to have the following of symbolic links enabled in the cgi-bin directory and allow the web server user execute the scripts not owned by it. May be I am making things more complicated than they are. I would be glad to use any other means to achieve my goal. Thanks in advance for your help. *I asked this on stackoverflow and some one suggested that I could ask this on serverfault.

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  • pfSense routing between two routers with shared network

    - by JohnCC
    I have a network set-up using two pfSense routers arranged like this:- DMZ1 WAN1 WAN2 DMZ2 | | | | | | | | \___ PF1 PF2___/ | | | | \___TRUSTED___/ Each pfSense router has its own separate WAN connection, and a separate DMZ network attached to it. They share a common TRUSTED LAN between them. The machines on the trusted network have PF1 as their default gateway. PF1 has a static route defined to DMZ2 via PF2, and PF2 has a static route to DMZ1 via PF1. There is NAT to the WAN but internal networks (DMZ1/2 and TRUSTED) use different RFC1918 subnets. I inherited this arrangement, and all used to work fine. I made a config change to PF1 (relating to multicast), and machines on DMZ2 suddenly could not talk to TRUSTED. I rolled the change back, but the problem persisted. What I guess you'd hope would happen is that TCP packets would go DMZ2 - PF2 - TRUSTED and on return TRUSTED - PF1 - PF2 - DMZ2. That's the only way I can see it would have worked. However, PF1 drops the returning packets. I've verified this using tcpdump. I've worked around this by adding static routes to DMZ2 via PF2 to the servers on TRUSTED, but some devices on there do not support static routes so this is not ideal. Is there way to make this arrangement work decently, or is the design inherently flawed? Thanks!

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  • Looking for something to monitor an Internet Shared Connection in Windows XP

    - by thenewbie
    If someone knows a software with these features: Works from the tray area Very lightweight Works also in Windows XP (preferably workstation, nothing serverish required) Can show a bandwidth usage graph, where I can easily see each PC's usage I can inspect a computer's connections, find out the ports and applications that are using them (eg, all bandwidth is consumed by PC #3, that's running uTorrent.exe from port 33003) ...I'd happily check it out. I'm only sharing my connection with (at most) 4 computers, I'd prefer not having to add hardware or reinstall my system. Thanks in advance!

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  • (Windows 7) Shared External Drive Permission Issues

    - by connec
    So, say I share my system (C) drive through windows (E.g. properties -> Sharing -> Advanced Sharing -> Share this Folder). I can then access this drive at \\Comp\C on another networked computer - all is well. However, if I insert a removable (USB) disk, say "E", and proceed to share it the same way, when I attempt to access \\Comp\E (either directly or through browsing) I get an error: Windows cannot access \\Comp\E You do not have permission to access \\Comp\E. Contact your network administrator to request access. Now, the permissions (Advanced Sharing -> Permissions) are set with "Everyone" having read access (same as the internal drive), so this doesn't make a lot of sense. Also of note, I have an SSH server on my computer (through Cygwin) and even through SSH (logging in as an administrator user) I cannot access /cygdrive/e (although /cygdrive/c is accessible). As a final note, the drive is of course accessible on the host machine (E:\), and also at \\Comp\E on the host machine.

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  • Win7 Professional x64 16GB (4.99GB usable)

    - by Killrawr
    I've installed Corsair Vengeance CMZ16GX3M2A1600C10, 2x8GB, DDR3-1600, PC3-12800, CL10, DIMM and my BIOS picks up that there is 16GB, Windows says there is 16GB, CPU-z says there is 16GB. But it only says I can use 4.99GB out of 16GB. Motherboard is P55-GD65 (MS-7583) Supports four unbuffered DIMM of 1.5 Volt DDR3 1066/1333/1600*/2000*/2133* (OC) DRAM, 16GB Max Windows (Above screenshot specifies that I am on a System type: 64-bit OS) CPU-z Microsoft says that the physical memory limit on a 64 bit win7 professional operating system is 192GB. Dxdiag Run Command BIOS Screenshot #1 BIOS Screenshot #2 Why is my OS limiting me to just over a quarter of the available memory? is there anyway to increase it?

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  • Grouping data columns by shared values

    - by Lenna
    I don't know how to properly describe what I need to do, so I will give an example. A colleague has a data set in Excel like so: Col A Col B Col C aaaaa aaaaa bbbbb bbbbb ccccc ccccc ccccc ddddd eeeee The end result should be something like this: Col A Col B Col C aaaaa aaaaa bbbbb bbbbb ccccc ccccc ccccc ddddd eeeee Or even: Col A Col B Col C aaaaa Yes Yes No bbbbb Yes No Yes etc. (if it helps, the columns are protein extraction methods and the letters are protein IDs - we need to determine which proteins are extracted by which methods) My colleague is doing this by hand, but there is enough data that it would be really helpful to automate it. Is there a formula in Excel to do this automatically?

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  • Shared External Drive Permission Issues

    - by connec
    So, say I share my system (C) drive through windows (E.g. properties -> Sharing -> Advanced Sharing -> Share this Folder). I can then access this drive at \\Comp\C on another networked computer - all is well. However, if I insert a removable (USB) disk, say "E", and proceed to share it the same way, when I attempt to access \\Comp\E (either directly or through browsing) I get an error: Windows cannot access \\Comp\E You do not have permission to access \\Comp\E. Contact your network administrator to request access. Now, the permissions (Advanced Sharing -> Permissions) are set with "Everyone" having read access (same as the internal drive), so this doesn't make a lot of sense. Also of note, I have an SSH server on my computer (through Cygwin) and even through SSH (logging in as an administrator user) I cannot access /cygdrive/e (although /cygdrive/c is accessible). As a final note, the drive is of course accessible on the host machine (E:\), and also at \\Comp\E on the host machine.

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  • thought about shared storage (NFS, Lustre) [closed]

    - by user134880
    Possible Duplicate: Can you help me with my capacity planning? Now I habe small cluster with total of 8 nodes. 6 of them are computing nodes (apache and vmware) and 2 nodes are for storage. 2 storage nodes are identical. Each storage server is linux box with 8 x 1Tb WD RE4 in soft raid 10. 1st box is master and 2nd is slave. Data is mirrored with DRDB. We export NFSv4 shares to Apache (for document root) and iSCSI to Vmware. Now all is working pretty good and stable. But it will be soon time to upgrade our system. I have been thinking of Lustre. Does some one has any real experience with Lustre or NFS medium clusters? Will it be good idea just to upgrade server and change hdd's to 3Tb ? With NFS we will always have only 2 servers to maintain (one primary and one slave). Thanks. QUESTIONS: 1) Does some one used Lustre? In production? I have seen a lot of info about how it is hard to setup Lustre because you need to compile own kernel and patches. It's answers from newbies. Is there some one who has used Lustre for some period of time? 2) About disk upgrades - it's only description of strategy. I'm not asking if it is enough 3Tb or not. I just ask if it is right just to replace hdds instead of adding new server (like with Lustre) Thanks again.

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  • centos server shared files

    - by Kyle Hudson
    Hi, I am wanting to implement a multi-server specialised hosting environment. I currently have a cloud solution comprising of 3 centos boxes (2 lamp web servers, 1 mysql). What I am wanting to do is, implement a 5 server solution where they is 3 web servers, 1 mysql box and a fileshare. Basically I want the fileshare to host all the web files for the servers, the caching will remain on the individual servers and the sessions will be stored in mysql. So what I am asking is how do I map the servers to share the same "docroot"? Is it NFS? if so whats the best way about doing this? Thanks in advance.

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  • Why aren't there 8gb RAM modules yet?

    - by user49951
    Why is RAM module development seemingly stuck at the same size for a while now (a couple of years)? I bought 2x2gb modules 2 years ago, and now it's all the same size, with prices even bigger. I want more memory, because I work a lot on my computer and I just need it. What is going on? Hardware/memory progress was being made constantly until these couple of years, and I'm a big computer user for over 15 years. Why isn't here 4gb/8gb modules yet? I would gladly replace my DDR2 motherboard for a DDRX one if it had at least 4gb DDRX modules for a reasonable price. Now we have a situation with very cheap usb drives reaching 64gb size, and a ram modules with pathetic 2gb size. Sounds like some sort of conspiracy.

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  • Windows 7 unreasonable ram usage

    - by Deus Deceit
    I have a fresh install of windows 7, and my ram in normal startup goes up to 2.5 GB. I looked at task manager, and there's at least 1.5 GB missing from there and in resource monitor as well. No indication of what's using that ram. Can someone tell me how I can find out what's consuming my memory? I believe it's a virus but none of the free antivirus programs tracked it down. EDIT I added the pictures bellow. If this is normal usage of windows 7 as some answers imply... then I don't get this at all. P.S My windows 8 Installation was running bellow 2.5 gb actually it was 1. something, until recently that I transferred some files from another computer which had the same problem that mine has now. I deleted windows 8 and installed 7, since i would do that anyway. And now I'm getting high memory usage in windows 7 as well.

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  • How to reliably mount a shared folder /volume/folder at boot up

    - by Tanmay
    Following is my sample.sh in /usr/local/bin/ #!/bin/sh mkdir -p /Volumes/folder mount -t afp -o rw afp://user:password@server_name/folder_name /Volumes/folder Following is my com.apple.sample.plist in /Library/LaunchAgents/ ?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>com.apple.sample</string> <key>ProgramArguments</key> <array> <string>/usr/local/bin/sample.sh</string> </array> <key>RunAtLoad</key> <true/> </dict> </plist> Where as when I am able to run sample.sh independently and is working fine. Also I have tried using launchd.conf as mkdir -p /Volumes/folder mount -t afp -o rw afp://user:[email protected]/testsuites /Volumes/folder Still not working.

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  • Updating shared files across computers

    - by murgatroid99
    I have a file server running Windows Server 2008 and a couple of laptops running Windows 7 on a network. There are a large number of files that all users will need access to. My plan is to have the files on both the server and the laptops because the users will need to access the files in places with no Internet access. I also want any changes made to the files on any of the laptops to propagate to the server and then propagate to the other laptops whenever they connect to the network. Should I do this with a scheduled batch script with a few xcopy commands or is there a better way to do it?

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  • Tomcat directly serve static (css, js) files shared by multiple applications

    - by Josvic Zammit
    I'm using the ExtJS framework which has a bulk of js and css files that are used for all apps. I intend to share these between a number of web applications (different war files). For this reason I would like to serve ExtJS js and css directly from the web server, in my case Tomcat6, which can be used to serve static files, as in this helpful link. Therefore I put my files under /var/lib/tomcat6/webapps/ROOT/extjs/. The static files that are directly under that directory are served correctly, e.g. /extjs/ext.js correctly serves the file at /var/lib/tomcat6/webapps/ROOT/extjs/ext.js. However files in lower-level directories, for example /extjs/welcome/css/welcome.css, which should serve the file at /var/lib/tomcat6/webapps/ROOT/extjs/welcome/css/welcome.css, return a 404. TL/DR Tomcat serves static files only at top-level directory. A 404 is returned for files deeper in the hierarchy. Config file contents: server.xml application's web.xml

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  • How much ram to be able to convert large (5-6MB) jpegs? [closed]

    - by cosmicbdog
    I've got a project where we want to be processing large jpegs (5-6MB) with apache and php (using GD library). My understanding is that the server converts the image into a BMP making it quite ram heavy and currently we're unable to do it with our 1gb of memory. Here's the error we get: Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 17408 bytes) How much ram should we be looking at running with to process images of this size? Edit: As Chris S the purist highlighted below, my post is apparently vague. I am doing the most basic and common manipulation of an image, say turning it from a 4352px x 3264px jpg of 5mb in size, to a 900px x 675px file.

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  • Installing multiple versions of a shared library

    - by nsfyn55
    I am running ubuntu 10.04 and I want to use tmux 1.6. tmux has a dependency on libevent 2. My solution was to compile libevent2 and drop into /usr/local/lib then compile tmux against this lib and drop into /usr/local/bin. This works great until...I restart. This is just an assumption on my part but it seems that other binaries are now linking to the libevent2 library presumably because its on the library path. Because there are 60+ packages with libevent1 dependencies this causes my install to basically lose its mind. Is there an idiomatic way to approach running an application that has a core library dependency on a different version? Should I just statically link the lib?

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  • Unix / linux permissions setup for shared hosting with Apache

    - by weiyin
    I'm in the process of setting up a server from a clean CentOS 5 install. What is the best permission structure (users, groups, unix permissions) for running a single instance of apache for multiple users? Ideally, it should satisfy these requirements: Each user's websites are stored in a subdirectory of their home directory. Users can edit files and permissions. Apache can read the websites of all users. No user can read the website files of other users. Bonus question: how to add PHP and/or Perl and/or Ruby to Apache without allowing any users to access any other user's files?

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  • A require a server hosting package that would be suitable for several .net managed applications, accessed only by me

    - by user67166
    Hello, I currently run a server at home consisting of SQL Server 2008 .net Framework 2010 VPN Connection ASP.net Web Services running around 5-6 applications supporting a financial trading system that i regularly use. THe only user is me. Recently the requirement to have these applications running in a 24/7 100% uptime (or 99%) environment has become important. No longer can I both meet this requirement and host my server at home on my network - so i am looking to move to a dedicated hosting company. After some research, the only real companies I can find offering such services are geared towards company web-space hosting. I don't need 1TB+ bandwidth, what i need is CPU, Memory and as much control over the environment as possible. Does anyone have any examples of such a service? Thanks in advance.

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  • Diagnosing PC crashes (most often while using shared folders or torrents)

    - by Dyppl
    For the last few weeks my PC (pretty old P4 with WinXP SP3) has been crashing randomly. It just suddenly reboots instanteneously. It feels hardware-related but I wasn't able to determine wether it's software or hardware that causes it. I did notice a pattern though: it's more likely to crash when I copy a lot of files over network or have uTorrent running, but sometimes it crashes when I am not doing anything with it. Copying files from it over network causes it to crash in 1 to 10 minutes almost every time. Using torrents causes it to crash every 1-3 hours. With neither or that on it crashes every 24 hours or so. I ruled out the following probable causes: PSU (I bought a new one and turned off most of the drives so the power is sufficient 100%) Bad HDD or interface cable on my SATA disk from which I was originally copying the data over network (bought new SATA cable and later yanked out the HDD completely, PC still crashes without it) Video adapter (AGP slot is now empty, using the onboard VGA at the moment) Network adapter (removed it from PCI, using onboard LAN) CPU (I think: I changed the termopaste and it's temperature is below 50C) RAM (I think: I ran Memtest86 and it didn't show any errors) At the moment I only have only one system HDD and DVD drives, a mouse and a keyboard plugged in. The fact that it crashes most often when I use network extensively makes me think that maybe it's software related (I removed the network adapter from PCI and now am using an onboard one, so network hardware is unlikely to cause problems). I am now pondering system reinstall but it's not a pleasant solution so I decided to ask wether there are better ideas first. If someone can share a good diagnostic tool it would be great because I didn't find anything good. Thanks in advance, I hope that "help to diagnose" questions aren't entirely banned here. EDIT: Motherboard is actually ~4 years old as I replaced it back in 2007

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  • SQL SERVER – Guest Post – Jonathan Kehayias – Wait Type – Day 16 of 28

    - by pinaldave
    Jonathan Kehayias (Blog | Twitter) is a MCITP Database Administrator and Developer, who got started in SQL Server in 2004 as a database developer and report writer in the natural gas industry. After spending two and a half years working in TSQL, in late 2006, he transitioned to the role of SQL Database Administrator. His primary passion is performance tuning, where he frequently rewrites queries for better performance and performs in depth analysis of index implementation and usage. Jonathan blogs regularly on SQLBlog, and was a coauthor of Professional SQL Server 2008 Internals and Troubleshooting. On a personal note, I think Jonathan is extremely positive person. In every conversation with him I have found that he is always eager to help and encourage. Every time he finds something needs to be approved, he has contacted me without hesitation and guided me to improve, change and learn. During all the time, he has not lost his focus to help larger community. I am honored that he has accepted to provide his views on complex subject of Wait Types and Queues. Currently I am reading his series on Extended Events. Here is the guest blog post by Jonathan: SQL Server troubleshooting is all about correlating related pieces of information together to indentify where exactly the root cause of a problem lies. In my daily work as a DBA, I generally get phone calls like, “So and so application is slow, what’s wrong with the SQL Server.” One of the funny things about the letters DBA is that they go so well with Default Blame Acceptor, and I really wish that I knew exactly who the first person was that pointed that out to me, because it really fits at times. A lot of times when I get this call, the problem isn’t related to SQL Server at all, but every now and then in my initial quick checks, something pops up that makes me start looking at things further. The SQL Server is slow, we see a number of tasks waiting on ASYNC_IO_COMPLETION, IO_COMPLETION, or PAGEIOLATCH_* waits in sys.dm_exec_requests and sys.dm_exec_waiting_tasks. These are also some of the highest wait types in sys.dm_os_wait_stats for the server, so it would appear that we have a disk I/O bottleneck on the machine. A quick check of sys.dm_io_virtual_file_stats() and tempdb shows a high write stall rate, while our user databases show high read stall rates on the data files. A quick check of some performance counters and Page Life Expectancy on the server is bouncing up and down in the 50-150 range, the Free Page counter consistently hits zero, and the Free List Stalls/sec counter keeps jumping over 10, but Buffer Cache Hit Ratio is 98-99%. Where exactly is the problem? In this case, which happens to be based on a real scenario I faced a few years back, the problem may not be a disk bottleneck at all; it may very well be a memory pressure issue on the server. A quick check of the system spec’s and it is a dual duo core server with 8GB RAM running SQL Server 2005 SP1 x64 on Windows Server 2003 R2 x64. Max Server memory is configured at 6GB and we think that this should be enough to handle the workload; or is it? This is a unique scenario because there are a couple of things happening inside of this system, and they all relate to what the root cause of the performance problem is on the system. If we were to query sys.dm_exec_query_stats for the TOP 10 queries, by max_physical_reads, max_logical_reads, and max_worker_time, we may be able to find some queries that were using excessive I/O and possibly CPU against the system in their worst single execution. We can also CROSS APPLY to sys.dm_exec_sql_text() and see the statement text, and also CROSS APPLY sys.dm_exec_query_plan() to get the execution plan stored in cache. Ok, quick check, the plans are pretty big, I see some large index seeks, that estimate 2.8GB of data movement between operators, but everything looks like it is optimized the best it can be. Nothing really stands out in the code, and the indexing looks correct, and I should have enough memory to handle this in cache, so it must be a disk I/O problem right? Not exactly! If we were to look at how much memory the plan cache is taking by querying sys.dm_os_memory_clerks for the CACHESTORE_SQLCP and CACHESTORE_OBJCP clerks we might be surprised at what we find. In SQL Server 2005 RTM and SP1, the plan cache was allowed to take up to 75% of the memory under 8GB. I’ll give you a second to go back and read that again. Yes, you read it correctly, it says 75% of the memory under 8GB, but you don’t have to take my word for it, you can validate this by reading Changes in Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2. In this scenario the application uses an entirely adhoc workload against SQL Server and this leads to plan cache bloat, and up to 4.5GB of our 6GB of memory for SQL can be consumed by the plan cache in SQL Server 2005 SP1. This in turn reduces the size of the buffer cache to just 1.5GB, causing our 2.8GB of data movement in this expensive plan to cause complete flushing of the buffer cache, not just once initially, but then another time during the queries execution, resulting in excessive physical I/O from disk. Keep in mind that this is not the only query executing at the time this occurs. Remember the output of sys.dm_io_virtual_file_stats() showed high read stalls on the data files for our user databases versus higher write stalls for tempdb? The memory pressure is also forcing heavier use of tempdb to handle sorting and hashing in the environment as well. The real clue here is the Memory counters for the instance; Page Life Expectancy, Free List Pages, and Free List Stalls/sec. The fact that Page Life Expectancy is fluctuating between 50 and 150 constantly is a sign that the buffer cache is experiencing constant churn of data, once every minute to two and a half minutes. If you add to the Page Life Expectancy counter, the consistent bottoming out of Free List Pages along with Free List Stalls/sec consistently spiking over 10, and you have the perfect memory pressure scenario. All of sudden it may not be that our disk subsystem is the problem, but is instead an innocent bystander and victim. Side Note: The Page Life Expectancy counter dropping briefly and then returning to normal operating values intermittently is not necessarily a sign that the server is under memory pressure. The Books Online and a number of other references will tell you that this counter should remain on average above 300 which is the time in seconds a page will remain in cache before being flushed or aged out. This number, which equates to just five minutes, is incredibly low for modern systems and most published documents pre-date the predominance of 64 bit computing and easy availability to larger amounts of memory in SQL Servers. As food for thought, consider that my personal laptop has more memory in it than most SQL Servers did at the time those numbers were posted. I would argue that today, a system churning the buffer cache every five minutes is in need of some serious tuning or a hardware upgrade. Back to our problem and its investigation: There are two things really wrong with this server; first the plan cache is excessively consuming memory and bloated in size and we need to look at that and second we need to evaluate upgrading the memory to accommodate the workload being performed. In the case of the server I was working on there were a lot of single use plans found in sys.dm_exec_cached_plans (where usecounts=1). Single use plans waste space in the plan cache, especially when they are adhoc plans for statements that had concatenated filter criteria that is not likely to reoccur with any frequency.  SQL Server 2005 doesn’t natively have a way to evict a single plan from cache like SQL Server 2008 does, but MVP Kalen Delaney, showed a hack to evict a single plan by creating a plan guide for the statement and then dropping that plan guide in her blog post Geek City: Clearing a Single Plan from Cache. We could put that hack in place in a job to automate cleaning out all the single use plans periodically, minimizing the size of the plan cache, but a better solution would be to fix the application so that it uses proper parameterized calls to the database. You didn’t write the app, and you can’t change its design? Ok, well you could try to force parameterization to occur by creating and keeping plan guides in place, or we can try forcing parameterization at the database level by using ALTER DATABASE <dbname> SET PARAMETERIZATION FORCED and that might help. If neither of these help, we could periodically dump the plan cache for that database, as discussed as being a problem in Kalen’s blog post referenced above; not an ideal scenario. The other option is to increase the memory on the server to 16GB or 32GB, if the hardware allows it, which will increase the size of the plan cache as well as the buffer cache. In SQL Server 2005 SP1, on a system with 16GB of memory, if we set max server memory to 14GB the plan cache could use at most 9GB  [(8GB*.75)+(6GB*.5)=(6+3)=9GB], leaving 5GB for the buffer cache.  If we went to 32GB of memory and set max server memory to 28GB, the plan cache could use at most 16GB [(8*.75)+(20*.5)=(6+10)=16GB], leaving 12GB for the buffer cache. Thankfully we have SQL Server 2005 Service Pack 2, 3, and 4 these days which include the changes in plan cache sizing discussed in the Changes to Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2 blog post. In real life, when I was troubleshooting this problem, I spent a week trying to chase down the cause of the disk I/O bottleneck with our Server Admin and SAN Admin, and there wasn’t much that could be done immediately there, so I finally asked if we could increase the memory on the server to 16GB, which did fix the problem. It wasn’t until I had this same problem occur on another system that I actually figured out how to really troubleshoot this down to the root cause.  I couldn’t believe the size of the plan cache on the server with 16GB of memory when I actually learned about this and went back to look at it. SQL Server is constantly telling a story to anyone that will listen. As the DBA, you have to sit back and listen to all that it’s telling you and then evaluate the big picture and how all the data you can gather from SQL about performance relate to each other. One of the greatest tools out there is actually a free in the form of Diagnostic Scripts for SQL Server 2005 and 2008, created by MVP Glenn Alan Berry. Glenn’s scripts collect a majority of the information that SQL has to offer for rapid troubleshooting of problems, and he includes a lot of notes about what the outputs of each individual query might be telling you. When I read Pinal’s blog post SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28, I noticed that he referenced Checking Memory Related Performance Counters in his post, but there was no real explanation about why checking memory counters is so important when looking at an I/O related wait type. I thought I’d chat with him briefly on Google Talk/Twitter DM and point this out, and offer a couple of other points I noted, so that he could add the information to his blog post if he found it useful.  Instead he asked that I write a guest blog for this. I am honored to be a guest blogger, and to be able to share this kind of information with the community. The information contained in this blog post is a glimpse at how I do troubleshooting almost every day of the week in my own environment. SQL Server provides us with a lot of information about how it is running, and where it may be having problems, it is up to us to play detective and find out how all that information comes together to tell us what’s really the problem. This blog post is written by Jonathan Kehayias (Blog | Twitter). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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