November 27, 2012 at 9:27 am
Hi.
We have a big concern with VMWARE. We are running over VMWARE windows server 2008 (domain controller and DNS). We also run SQL Server 2005 that has a 25 Gb database on a LAN with 15 clients (4 are points of sale continuosly working). The server has raid 5 and 4 GB RAM. All the network it is compliant certified. Our problem: We were on 2003 server for a long time experincing a high demand and time response delay on physical disk I/O. Can be virtualization part of this problem? Any advice it is welcome.
Regards, Joe
November 27, 2012 at 11:18 am
Virtualization can add to latency, especially with older versions.
Whether that's the situation you are running into is something that would take actually digging into the server to determine. It's not really something that can be diagnosed via a forum. It depends on I/O bandwidth, wait types, how the virtual disks are configured, how the physical disks are attached to the physical server, load from other VMs on the server hardware, other forms of resource contention, and a host of other variables.
Virtualizing SQL Server can be very successful, but it can also be tricky to get right.
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November 28, 2012 at 10:46 am
Thanks. Any reading or video recommendations?
November 29, 2012 at 6:47 am
I'd start with: http://www.vmware.com/files/pdf/sql_server_best_practices_guide.pdf
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November 30, 2012 at 6:48 am
Brent Ozar has some good information on using VMWare and SQL Server: http://www.brentozar.com/archive/2011/05/keys-deploying-sql-server-on-vmware/[/url]. Note this point on his Top Ten List:
8. Avoid 1Gb iSCSI for storage. While this cheap and easy-to-use storage works great for most servers, it doesn’t work as well for SQL Server. If you’re happy with the speed of SQL Server running on local storage, you can be in for a rude surprise with 1Gb iSCSI.
We run our production DB on VMWare and have been very happy with its performance, despite using 1Gb iSCSI. Our DB is small, though, and we have lots of extra RAM on our VMWare farm. I don't administer the VMWare servers nor the SAN, so I don't have a lot to offer: we hired a consultant to help us get the VMWare servers set up, and we're very glad we did.
But it seems to me that trying to run VMWare with only 4 Gb of RAM is asking for trouble. You'd have to do some testing to see if your SQL server is swapping to disk a lot (Buffer Cache Hit Ratio), in turn contributing to the I/O latency you describe. That RAM has to be shared by every virtual machine on your VMWare server(s).
Post back if you find a solution,
Rich
November 30, 2012 at 2:40 pm
This is an excellent document to read. Thanks for sharing it. I already gave it to the guy who is in charge of the VMWARE environment.
Joe
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