topic Re: No CPU and Memory oversubscription Cisco UC in ESXi Discussions

No CPU and Memory oversubscription Cisco UC

kopper27 — Mon, 20 Apr 2015 23:14:41 GMT

hi guys

there's this project where Cisco Communications are needed and the requirements says:

All VMs require a one to one mapping between virtual hardware and physical hardware

Unified Communications Virtualization Sizing Guidelines - DocWiki

so my question what is to assign let's say 2 physical cores to a VM?

document say:

Must map 1 VM vCPU core to 1 physical CPU core.

and what about VM vRAM to pRAM? using reservations or limits?

document says:

Must map 1 GB of VM vRAM to 1 GB of physical RAM. Memory oversubscription is not supported for Cisco UC VMs.

thanks a lot

Re: No CPU and Memory oversubscription Cisco UC

NuggetGTR — Tue, 21 Apr 2015 01:52:42 GMT

Looking at the wiki they are basically saying no over subscription as in

if you have a host with 12 total physical cores, then you can deploy any combination of virtual machines where the total number of vCPU on those virtual machines adds up to 12.

For memory, reservation would work but sounds like CPU would be the limiting factor in this instance.

Re: No CPU and Memory oversubscription Cisco UC

kopper27 — Tue, 21 Apr 2015 02:00:48 GMT

yeah I have to apply both cpu and memory dedicated resources, do you know how to map vCPU to pCPU?

thanks

Re: No CPU and Memory oversubscription Cisco UC

NuggetGTR — Tue, 21 Apr 2015 03:25:29 GMT

well apart from not provisioning more vCPU then pCPU on the host, CPU reservation would have to do, while this ensures the resources it still competes for execution time if the host is over provisioned as a whole.

CPU affinity is an option but not recommended and cant be used in a DRS cluster anyway.