VCS vCPU reservation?

[Tommer Catlin]

Any see this in the guide?

http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Virtual_Machine_Deployment_Guide.pdf

VCS  IaaS  deployment  minimum requirement  are

-VM Host operational and running ESXi 4.1 or ESXi5.0 (Update 1)

-6GB of RAM per VCS VM

-132GB disc space per VM (for a 4GB virtual disc 1 and  a 128GB virtual disc 2)

-2 Cores reserved per VCS VM; each core >= 2GHz processor

-vCenter or vSphere operational

What is the "Reservered" cores.  Is this really required??

[Alok Jaiswal]

Hi Tommer,

When you create a VM instance it gives an opiton to select the number of CPU's and cores!!

obvisously the document says to reserve it so you should reserve it. it is tested for giving best performance.

although if its a test setup you can certainly play around with it. I used to change the VM req for CUCM and sometimes i run into issues.

Thanks

Alok

[Tomonori Taniguchi]

Current VM VCS may use full 2 Core processor and yes you will require to configure VM application assigned 2 core on VM VCS application.

VM VCS support co-resident applications (any other VMs occupying same host) with following conditions:

• No oversubscription of CPU: 1:1 allocation of vCPU to physical core per VM <-- 2 core with current VM VCS specification and this may change in future release version depend on deployment scenarios.
• No oversubscription of RAM: 1:1 allocation of vRAM to physical memory per VM
• Sharing disk storage subsystem is supported with correct performance (latency, BW) characteristics.

[Tommer Catlin]

I understand it will it will use (2) vCPU, but do they really need to be reserved?.   Tomonri, being that you are from Cisco, is this the supported statement from the BU on how VCS is to be configured?   VMware teams see "reserved" and they freak out.   If you look at the OVA DocWiki, nothing says "reserved"  just what is required.  So the terms "required" and "Reserved" seem to confuse VMware teams.

If there a reason for the reservations in VMware, is because of the video transcoding required? (or possibly)

Thanks much for your help!

[Fred Nielsen (ePlus)]

To clarify, the thing you reserve re: CPU in vSphere are clock cycles and not really core themselves.. so I interpret the above to mean that the machine needs to be configured with 2 vCPUs and a 4000 Mhz resource reservation for the vmachine.

On the question of whether you really need CPU reserved: if you expect those cycles to be available to your realtime application when it requests them, this is way to enforce it (outside of carefully and deliberately overbuilding your compute farm, which is really another kind of reservation).  Cisco can't certify scalability and performance otherwise.  If DC managers deviate from the spec, bad things can happen to things like media streams and DB synchronization when the guests start competing for CPU time, in the case of VCS notably your traversal media streams might suffer.  I've noticed that TAC engineers are validating vmachine configs up front when dealing with a case tied to a performance issue.

This is no different than the other UC workloads for which OVAs are provided - if you dig into what those OVA's do you see that they also enforce CPU resource reservations.

[Tomonori Taniguchi]

Frederick has already made good reply about vCPU.

Not sure the “Reserved” is not common explanation or description to be used for VMWare technology, but point that VM VCS should not be in “Ready Queue” status.

Some of VCS process is time sensitive (i.e. cluster peer communication) and need real time process for queue.