vSphere Storage Appliance

What utility should I use to test disk performance of the VM (Crystalmark, IOmeter, etc)? Would testing the disk of a VM give me an inidication as to which data store is performing better if I migrate the vm and test the vm's disk on the different data stores?

IOmeter, Crystalmark, IOzone, hdparm are all good choices.

Testing the disk in the VM would give you some indication of datastore performance, yes.  Be aware that lots of things effect the numbers you get:  IO size, R/W ratios, queue depth, filesystem cache (if any), virtual scsi driver, array design, other workloads, etc.

bateslabel wrote:

Would testing the disk of a VM give me an inidication as to which data store is performing better if I migrate the vm and test the vm's disk on the different data stores?

You could even attach several virtual disks to the VM, each vmdk on a different datastore and try out the performance differences.

VMware has said they use IOmeter for almost all internal disk performance testing.