I was recently involved with troubleshooting some performance issues running PS 4.5 inside VM’s on ESX 4.0.
When comparing the performance of a physical server to that of the VM, certain login tasks would be completed 20/30 seconds slower on the VM. We performed the usual step by step troubleshooting approach tweaking memory, network, CPU, disk placement, even running 1 VM on a host but we couldn’t reduce this time.
Then, we looked at enabling MMU on the guest. By default the setting is automatic, so I still don’t understand why it didn’t kick in, but once we forced the setting, the VM matched the original physical Citrix server on all tests.
The only this we couldn’t achieve was the same quantity of users on the VM. We went from 50 per physical server to 25 on the VM. But, we were able to run 12 virtual machine instances on a single ESX host, so actually we saw a large increase in the number of users per physical box!
The VM configuration we used was 2 x vCPU, 4GB RAM. We also enabled the vmxnet3 cards which appeared to improve performance slightly.
