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Fredzone
Contributor
Contributor
‎10-01-2012 01:13 AM

Best ratio VMs/Cores for XenDesktop running on ESXi 5.0u1

Hello All,

I would to calculate the number of VMs for a XenDesktop 5.x environment based on vSphere 5.0u1.

The physical servers are HP BL460c G7 (2x Quad Core, 128GB Ram). The SAN is a HP MSA P2000G3 with SAS connectivity.

The VM config is 2 vCPUs and 1.5 GB Ram.

My main concern is about the LCPUs. Should I take care of the HT cores in the calculation or not? If yes, it has to be done on 16 LCPUs and on 8 LCPUs if not. I didn't find an "official" statement of VMware about the HT cores. If there is a document, I'm interested.

Thanks in advance,

Frédéric

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jklick
Enthusiast
Enthusiast
‎10-03-2012 10:05 AM

When you're trying calculate your VCPU:LCPU ratios, you'll want to use the hyperthreaded value of 16. Now, this is assuming that people aren't going to be doing a lot of CPU intensive (*cough* streaming HD video *cough* *cough*) tasks, in which case you'll run out of GHz before you run out of LCPUs. Smiley Happy

A common rule of thumb that I've seen is that you can get about 3 VCPUs per LCPU. However, I've seen seen people do good at much higher ratios as well as issues at lower ratios. The way to know for sure is to measure CPU Ready on your virtual machines and make sure that neither of their vCPUs get about 1000 ms on a real-time vCenter graph.

I recently wrote about monitoring CPU Ready and you might find it useful: http://www.vkernel.com/reader/items/configuring-cpu-ready-alarms-vcenter

Let me know if this is what you were looking for or if you have additional questions.

@JonathanKlick | www.vkernel.com