Session Title: “Citrixand VMware: How these Two Technologies Work Together to Provide More Efficient Computing”

So far, this has been the best breakout session I’ve attended. The presenters did a lot of extensive testing of Citrix Presentation Server inside a VM on both ESX 2.5.X and 3.0.X.

The Physical server that they used was a HP DL585 with 4 AMD dual-core Processors and 32GB of RAM. The VM they used was had 1vCPU and 3.5GB of RAM, running Windows 2003 (32bit), along with Citrix Presentation Server 4.

Their test script did the following loop:

Opened a MS Word document and typed for 11-15 minutes.
Paused shortly then repeated.

This script simulated a single users and a new instance was started every 30 seconds. This helped to simluate multiple users accessing the Citrix Server.

This test was done on both ESX 2.5.X and 3.0.X. The results were interesting:

With ESX 2.5.X 80 users ran the CPU at 85%

With ESX 3.0.X 140 users ran the CPU at 80%

(Great Kudo’s for ESX 3.0.X)

The presenters were very clear that they weren’t trying to say you can get 140 users on a Citrix VM, individual results may vary depending on what the users are doing. It also shows the performance improvement from 2.5.X to 3.0.X.

To get optimal performance from a Citrix VM the presenters offered the following tips:

* In 2.5.X the Terminal Server Switch was needed, but not in 3.0.X

* You should disable Transparent Page Sharing. Go into Advanced Setting and change the following:
Mem.ShareScanTotal = 0
Men.ShareScanVM = 0

Note: This will effect the entire ESX server

* Change:
Mem.ShareScanThreshold = 4096

(Sorry, the slide went to fast to write down their notes on why.)

* Dual Proc VM’s are not recommended. Multiple vCPU’s create more of an overhead than it’s worth.

* Disable Hyperthreading, although they won’t guarantee that this will improve performance. You can either disable hyperthreading for the entire ESX server or for a specific VM by editing the vmx file:

shed.cpu.htsharing = none

* Use the LSI Logic SCSI adapter.

* Disable COM, LPT, & USB

* Disable auto-detect of CDrom

* Disable Visual Effects in Windows

* Do not over allocate RAM. If the server has 32GB of RAM, only allocate 32GB for the VM’s.