Recommended drive configuration for various virtual machines?

You didn't mention your hypervisor, but I'd suggest to go VMware if you're still needing to decide.

If you're wanting to use a hyper-v solution and are going for Windows Server (2008 R2), you'll need to make sure you get Enterprise or Datacenter as failover of VMs from one host to another requires shared storage, which means you need to run a cluster (and Standard cannot be clustered; only Enterprise or Datacenter can cluster).

Raid basics come into play here.

Raid 10 offers great write performance as there is no parity to be calculated; it just dumps it on the disks (but mirrored). However, when reading you're only getting the read performance of half the number of drives.

Raid 5 offers great read performance as you're reading from all but 1 of the drives (each stripe this 'skipped' drive moves over, but you're still effectively reading from all but 1 drive). However, when writing the raid parity needs to be calculated before it can be written to disk.

Per EMC's best practice guides, the turning point is at 30%/70%; if 30% or more of your IO is writes (70% or less is reads) then raid 10 is the better choice.

On it's own this doesn't give you an answer, but using this info one option may be to do something like this:

- disk 0-4 as a 5-disk raid 5 for 'low write VMs'

- disk 5-10 as a 6-disk raid 10 for 'high write VMs'

- disk 11 as a hotspare

If you're running (planning to run) VMware ESX/ESXi, and your disks are pretty large, you may need to create multiple virtual disks in each diskpool to prevent from going over the 2TB (2048GB) size per virtual disk, as ESX/ESXi cannot work with disks over 2TB.

Thanks so much for your reply, that does help a lot.  Another question, is there any advantage to creating a separate disk pool for all of the virtual C drives?  RAID level aside, does grouping VHDs on disk pools by function gain anything?