It depends on the number of users and the workload of the Citrix / TS servers.

We have virtual Citrix servers with 40 or so users on, and they report no problems. It completely depends upon the application(s) and their I/O requirements.

Chris

The bigest problem is CPU context switch. If you application is using a lot of CPU it's not a got idea to virtualize.
I had clients who virtualize citrix for 40/50 users on a blade (bl20p) whithout any problem and they try another application, 5 users can't work. You have tools to test context switch...
But when it works there is not problem, he show me vmotion with 40 uses on citrix VM, no deconnection!

Could you point us to one of these tools? I'm not being sarcastic, I just couldn't find any pointers with a quick internet search for context switch test tool.

I'm currently thinking about virtualising our Citrix farm (175 users currently, running on 3 x DL360 R01 & 3 x DL360 G3, upping to 200 users in new environment).

I am actually quite lucky in that I have a "choice" as we do have 4 x Quad-core / 10Gb BL460c's potentially allocated for the replacement Citrix farm but I can't help thinking that this would be a "waste" of good hardware and it's worth testing their virtualisation.

I read, with interest, the presentation from http://www.vmware.com/vmtn/vmworld/ (TAC9728: Citrix and VMware: How These Two Technologies Work Together to Provide More Efficient Computing) in which a test/demo illustrates running around 225 citrix sessions when installed natively on a DL585 with 4 x Dual Cores and managing 140 users in a citrix VM in ESX running on the same hardware.

They then go on to "claim" that this scales to around 110 users in 8 VMs on the same hardware!

Now, I know as well as the next man that demos rarely reflect real life, but it has to be admitted that there's a rather significant difference between 12 users per Citrix VM & 140!

I'd happily virtualise if I got acceptable performance with 30+ users (our current hardware struggles at over 40 users, especially the G1's).

At the end of the day, I can't decide between native on, say, 3 of the BL460s or throw ESX on each of them and have greater opportunities for application isolation & fault-tolerance.

Just need to find the time to create a test environment whilst I've got the hardware "lying around".

Regards,

Paul

Agree with everything you say!

One thing though is that I'd definitely not mix Citrix VMs with other VMs, I'd love to test, say, three 32bit Citrix VMs running on a quad-core box with 12Gb mem. As it happens, I have that hardware "lying around" at the moment, but what I don't have is time to "play"

Biggest issue in reality though is that even if you or I were to develop a test-lab, everyone knows that each site's app footprints & usage is likely to be very different at the end of the day...

Paul