I’d like to know if EVC would affect performance of the vms?

[beckham007fifa]

Hi Guys -

I am two heterogeneous clusters and I would like to have vapps across them. I want vms to move across when needed. Will this cost performance of the vms? I have huge vms sitting, 32GB ram being the smallest machine. Many Thanks.

Regards,

[RyanH84]

Hi,

I'm fairly confident that you won't be able to move your VM's across clusters if their EVC mode is different, unless you power down the VM an move them over. I think you could move from low to high EVC mode but then going back to the lower one you would have to power them off.

I do not think that you will see much of a performance hit in terms of the CPU processing capability, unless you have 2.0Ghz CPU in one cluster and 3.0Ghz CPU in another. To truely know, you'd probably have to run some VM's on each cluster and run some CPU bench-marking tools.

Generally, EVC modes enable heterogeneous clusters to become uniform by masking CPU features that might not be available to earlier CPU architectures. Take a look at this KB which help highlight the different features.

[iiToby]

Hi Beckham007fifa,

Yes EVC mode will affect performance, however is most cases almost immeasurably.

I would take a look at these two references from VMware, the describe the performance impact of EVC.

http://www.vmware.com/files/pdf/techpaper/VMware-vSphere-EVC-Perf.pdf

Does Enhanced vMotion Compatibility (EVC) Affect Performance? | VMware vSphere Blog - VMware Blogs

However the benefits of EVC vs not having EVC generally out weigh the performance impact, most long running clusters I have seen are running EVC.

Kind Regards

@iiToby

[beckham007fifa]

Thanks both of you. Appreciate that...