How do I configure RAID on a Virtual Server

You don't configure RAID partitions on the VM (well, you can, but that is not what you want to do).  All you need to do is carve out a partition on the VM.   The VM has no idea if you are exposing a RAID volume or JBOD.   It doesn't have to.

So since you are already presenting RAID partitions, then just do the same thing as if it is non-RAID.  

RAID is configured on the Physical Host server, so the VMs don't need to worry about it. RAID is primarily a hardware level technology, and it doesn't extend to VM configuration, but any VMs running on a Host server with a RAID array configured will be protected by that Array. You can configure software raid on the VMs, but it has to be done after the OS is installed and doesn't really provide much benefit.

Can you tell me how to configure software raid on the VM - for my knowledge base.  Also, it would be helpful to the DBA since this is a SQL server.  It would help him to be able to put logs and data on separate volumes.

if you do this, then it will result in a performance hit.

correct thing to do is use direct io to dedicate physical (non raid) disks to just this vm.  then you will benefit.  

but based on the q, you can't do that with your current config

Windows Server utilizes Dynamic Disks for Software RAID. http://www.techimo.com/articles/index.pl?photo=149 has a guide on how to achieve it, despite being pretty well out of date. Basically you would configure multiple drives assigned to the VM as dynamic volumes and Mirror, Stripe, etc. the drive in the Storage Management MMC.

dlethe,

>>but based on the q, you can't do that with your current config

I would need a SAN, DAS or some other type of external storage, correct?

Also, if you have an iSCSI SAN available, it's better (and easier) just to mount that directly to the VMs than it is to configure and store VHDs on the SAN, then mount them to the VM.

In order to do the direct I/O thing, you have to add more hardware, and nail it to the specific virtual machine.  I.e, you add a second RAID controller and additional disks and then tell VMware that it is married to the specific VM.  Then when you install the VM, you add drivers for the RAID controller as if it is a physical machine, and configure the logical devices as if this was a non-virtual machine.  If you do that, then the I/O for that machine would be shared with the other VMs.

Gentleman,

Thank you very much for sharing your expertise.  Much appreciated!

Alicia