Hi,
We did some tests before upgrading our SAN to find what is the best way to get greater VM disk performance. It's not about SAN performance itself, that's is OK for us, but from the VM perspective. The purpose is to get better user experience, get fastest response time when user open Outlook or web page for example. We found something we can't explain. There is a HUGE gap between performance on Linked Clones disk (C:\) and independant disk create for testing (E:\) on the same VM.
Here the test with IOmeter: "VDI test" => 80%/20% write/read, 80% random, 4K block, 16 IOs, 2 workers, 8GB disk size (iobw.tst)
Linked clones disk (C:\): 180-200 Iops
Independant disk (E:\): 1800-1900 Iops
Normal VM (outside "View"): 4500 Iops
It's obvious that VM in View environnement never reach the real disk performance that the SAN could deliver. Around 200 Iops it's not really bad but why this limit if we know it could be lot better? All the test was done on the same VM type, same LUN, after working hours. So, is there something with the mecanism of Linked Clones that brings this big penalty in term of disk performance or is there some rules that limit the disk usage of each VM? To increase performances, is there something we can look?
Here our environnement:
Vmware View 5.2
ESXi 5.1
SAN: Equallogic PS4100X
VM: Windows 7 SP1, 1.5Gb RAM, 2 vCpu
