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I need to deploy some vms for sql servers, how do you plan the san volumes ? put os, data & log files in different vmdk ? or different volumes ? or put all in same volume ?

Also , is it good advise to create many volumes or limit them to 1 or 2 ? ( sql-log, sql-data,files,os-vms,24hours, 5mins, no-replica )

thanks in advance.

Mark Henderson
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user40997
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3 Answers3

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  1. Follow Microsoft's best practices for SQL disks. Put OS, data, and logs onto separate VMDKs. http://technet.microsoft.com/en-us/library/bb402876.aspx

  2. Don't use more virtual CPUs than you have to.

  3. Align your partitions.

  4. Don't put too many VMs on the datastore that your SQL server is on.

JakeRobinson
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  • "Align your partitions." - could you explain this more ? – user40997 Aug 01 '10 at 14:53
  • Sure! When partitions are unaligned with their underlying systems, you double the amount of work needed per IO request. VMware does a great job explaining it in the following document. Now, I will say that you may not notice a difference unless you have some serious IO on the SQL server, but again, we are talking best practice. :D http://www.vmware.com/pdf/esx3_partition_align.pdf – JakeRobinson Aug 02 '10 at 06:07
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    To this I would add - Seperate VMDKs and Datastores is good, but if they're all coming from the same RAID Array, your performance is still going to be limited by the number of spindles, RAID configuration, and contention with other VMs running on that array. I'd advise setting up dedicated RAID arrays on your SAN for the data & logs, if you performance requirements really require it. Extra arrays on your SAN is additional management etc though, so only if you need it. Also pay heed to the saturation of your links to the SAN (number of fiber or iSCSI interfaces available). These matter. – Chris Thorpe Oct 24 '10 at 06:42
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From performance perspective, it is always a good practive to put OS, data, log and tempdb files on different drives

Nomad
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Hello, I need to deploy some vms for sql servers, how do you plan the san volumes ? put os, data & log files in different vmdk ? or different volumes ? or put all in same volume ?

It depends on your backup and performance needs. If you plan to use snapshots, your snapshot provider may need to have the data and log files on the same VMDK. If you need multipathing for faster SAN throughput, then you may need data files on several different VMDKs on separate underlying LUNs.

Also , is it good advise to create many volumes or limit them to 1 or 2 ? ( sql-log, sql-data,files,os-vms,24hours, 5mins, no-replica )

Again, depends on your backup and performance needs. Generally it's easier to lump these onto as few volumes as possible, but if you're doing volume-level snapshots with your SAN for extremely fast backups, you'll want to group VMs together based on their disaster recovery needs.

Brent Ozar
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