add vCPU to CUCM 9.x per CSCtu18692?

[kdotten36]

Bought a shiny new c220 and upgraded to CUCM 9.1.2 from an old HP MCS with 8.5.

Every night I'm getting a CPU Pegged error during backups from the gzip process.

I figure I can turn my cheek since it's off hours but TAC recommended adding a second vCPU to the VM per the Bug ID CSCtu18692.

We only have a 2 server cluster which hosts 320 users total, and it's being recommended to run a config designed for 7500 users?  The VM was already built per Cisco's OVA template design for 2500 users. 

Has anyone done this?  I'm debating whether to throw another cpu license at the thing or just swallow my pride over the new machine being unable to handle what the old one could.

Also on that note, TAC says it's safe to shut down, add the cpu and start back up, but I read another note on these forums that I should rebuild the whole VM and restore. 

[George Thomas · Accepted solution]

You should be ok to leave it at 1CPU but that will be up to you. a vCPU can be added by shutting down the machine adding it and then bring it back up. The only time you need to rebuild the VM is if you are trying to add vDisk space. 

[joeharb]

We are experiencing the same issues.  I have read/found mixed results on simply shutting down and adding the new vCPU.  Has anyone had issues with this?  I would rather not have to rebuild all the servers in our cluster if that can be avoided.

Please advise,

Thanks,

Joe

[Rob Huffman · Accepted solution]

Hi there,

+5 to my buddy George first off for his good tips

We have not done this procedure as we use the 7500 user OVA, but I thought these notes might help clarify this issue at hand. With the release of CUCM 9.1 the 2500 user OVA did make this change;

In Unified Communications Manager Release 9.1, the following changes were made to the OVAs:

Note

•

•The number of vCPU for the 2500 Limited User OVA changed from 1 vCPU to 2 vCPU

From;

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/rel_notes/9_1_2/CUCM_BK_C9FFFCD0_00_cucm-release-notes-912.pdf

And this note from the DocWiki;

Notes on 2500 user VM configurations

Note:

The 2500 user VM configuration with one vcpu may exhibit performance issues during CPU/IO-intensiveoperations (such as installs, upgrades, backups and CDR writes), or if your deployment has certain characteristics such as a large quantity of TFTP files. Changing the VM config to 2 vcpu is recommended as a prevention strategy. Otherwise you may deploy with one vcpu and be TAC-supported, but note that if the root cause of performance issues is found to be insufficient vcpu, Cisco TAC will ask that you change this to 2 vcpu. If your deployment is not experiencing any issues you are not required to change to 2 vcpu and may remain on 1 vcpu. From; http://docwiki.cisco.com/wiki/Virtualization_for_Cisco_Unified_Communications_Manager_%28CUCM%29#Notes_on_2500_user_VM_configurations

Cheers!

Rob

[kdotten36]

Thanks, I did see that, but in the OVA readme, there are 2 2500 user designs and the one they changed to 2 vCPUs is for the 60GB disk model, which refers to the HCS version.  Mine is not hosted so it should still fall into the 1 cpu design.  It was quite an internal struggle as I built the machine, I should've just gone with extra juice to begin with!  Thanks for the comments.

http://www.cisco.com/web/software/283088407/97505/cucm_9.1_vmv7_v1.6.ova.README1.txt

[Scott Leport]

Hi Rob,

Regarding this line:

"Otherwise you may deploy with one vcpu and be TAC-supported, but note that if the root cause of performance issues is found to be insufficient vcpu, Cisco TAC will ask that you change this to 2 vcpu"

Is a x2 vCPU on a 2500 OVA template a TAC supported solution?

Scott

[Rob Huffman]

Hi Scott,

Yes, that would be the recommended and TAC supported solution.

Cheers!

Rob