win7 performance in VM twice worse than real HW! WHY?

[martin3361]

Hi there

so just for kicks in tried 4.1 ESXi free license.

server HW - lenovo 2x quad E5520 Xeon+32Gig mem+ 70G 15kRPM/RAID0 SAS drives.

i setup a win7 pro 32bit as a ESXi VM and gave it 4GIG RAM, "highest" CPU shares allocation.

and when we run a set of tests, they take 2x longer then if I have the same win7 installed natively on this server.

... what do i do ?

help ....

what else can i provide you guys form the esxi to help this out.

[chriswahl]

Shares have no affect in this scenario because you only have 1 VM. Shares only count when there are multiple VMs trying to use the same resource (such as overcommited memory).

What sort of tests are you running? If your tests involve doing writes, I'd suggest looking at your raid controller to see if it has a battery backed write cache and is in write-back mode. Without this your write performance is going to suffer greatly when using ESXi as it will have to wait on the writes.

http://wahlnetwork.wordpress.com/2011/07/20/solving-slow-write-speeds-when-using-local-storage-on-a-...

[mcowger]

Also, whats teh config of your VM?  if you only gave it 1 vCPU, then it will perform much worse!

[umarzuki]

it's a VM, remember that.

[martin3361]

thanks - if the software does writes, it would have to do the same writes while in native win7 install, am i not understanding something? would the controller have to do the same function then too?

[martin3361]

missed that detail, it has 4 vCPUs

[Kahonu84]

Aloha,

Back off to one vCPU and see if that helps.