Questions regarding multiple PLM 11.x servers

[Nadav]

Hi everyone,

I have a few questions regarding having multiple PLM servers as opposed to a single PLM server installed on the CUCM Pub:

1) Is there any benefit to installing multiple PLM servers for a single cluster? If the PLM is on the Pub and the Pub goes down for any reason, I can't modify the CUCM DB and therefore the PLM isn't necessary during Pub outage. Is this correct?

2) I read that if installing multiple PLM servers, the MAC address for the VM where the PLMs are installed should be the same since the PLM licencing is fixed on the VM MAC address. When is this important if the PLM is installed on the Pub?

3) If I update a PLM server (request PAK, install licenses etc.), are the changes replicated across the different PLM servers in the cluster?

4) What benefit is there to removing a PLM after installing of a CUCM server? Is it a matter of saving disk space and ensuring that all licenses are managed from a single PLM?

Thanks for your time and thoughts!

[Rajan · Accepted solution]

Hi Hod,

AFAIK you can have only one PLM for managing the licenses of one CUCM cluster at a time either the one installed with the Publisher or a standalone one.

In case of pub being down, only thing which wont be available is that all license utilization details wont get synchronized to the latest but still CUCM has the details of the last sync which happened. Also you wont be able to add any new licenses during this time. Apart from this i dont foresee any issues wrt licensing when the PLM is down.

HTH

Rajan

[Nadav]

Hi Rajan,

I'm afraid I don't follow. If the publisher is down for a co-resident deployment, then the PLM would be down as well since they are on the same VM. Other CUCMs will continue to utilize the licences they are aware of, much like clusters pre 9.x.  Is that not so?

Is there any possible benefit to installing more than one PLM per cluster on the Publisher? After all it's a non-redundant application. 

[Chris Deren]

As already answered by others there is no benefit to multiple PLMs as a single cluster can only talk to one PLM anyway. If you lose your PLM it's not the end of the world as you will have 60 days to recover it and restore from backups which you should schedule daily just like other applications.

[Manish Gogna]

In addition to the useful info by Rajan, you may check the design guide which says

"Redundancy

Prime LM is deployed as a non-redundant application. In the event that the Prime LM application becomes unavailable (for example, if the Prime LM virtual machine is experiencing operating system issues and it cannot boot up), the customer has 60 days to restore the Prime LM application before license enforcement occurs. The applications will run for a period of 60 days without communication with the Prime LM.

For restoration of the Prime LM application, another installed Prime LM application (such as a co-resident instance) can be created by re-adding the product inventory to the new Prime LM application. Since the MAC address of the virtual machine running the new PLM application would be different, transferring the registration of the license file to this new Prime LM would be required. Alternatively, Prime LM can be restored from a Disaster Recovery System (DRS) backup. In this case, configure the same MAC address on the new and original Prime LM virtual machines, otherwise the license registration will have to be transferred to the new virtual machine. If license additions or changes have been made since the DRS backup, a new license file will have to be requested. A Prime LM co-resident backup can be restored only to a co-resident Prime LM application, and a standalone backup can be restored only to a standalone Prime LM."

Additionally

The main considerations for choosing between co-resident and standalone deployments center around administration and management. The main benefits of deploying Prime LM in a standalone configuration are as follows:

• Upgrading a standalone Cisco Prime LM is done independently from upgrading the applications (Unified CM or Unity Connection). Whereas, upgrading a co-resident configuration of Cisco Prime LM is done by upgrading the co-resident application, which upgrades the application and Cisco Prime LM at the same time
• Platform changes to Unified Communications applications (Unified CM or Unity Connection) might require changes to a co-resident Prime LM application. For example, a change in the MAC address would require transferring the registration of the license file(s) for a co-resident Prime LM; however, in the case of standalone Prime LM, platform changes such a MAC address change of the application virtual machine would not require transferring the registration of the license file(s).
• Administrative changes required on a standalone Prime LM will not impact the application servers. For example, on a co-resident configuration, having to upgrade or reboot the Prime LM would require an upgrade or reboot of the application.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab10/collab10/callpros.html#pgfId-1347951

Manish

[Deepak Rawat]

[+5] to Manish for sharing this wonderful piece of information. I always had doubts over this that why one would want to use standalone PLM opposed to co-resident one.

Regards

Deepak