CUCM 11.5 to 12.5 - Switch Version Options

TONY SMITH · ‎07-21-2020

Hi,

I asked this question when we did an upgrade in the past, and at that time it was commented that some changes to the process and the requirements for version switching were coming in with 12.x.

So I'd just like to check that for this upgrade it's still possible and supported to switch version as each server is upgraded, rather than a separate step after all servers are completed. The reason I want to do this is so we only have one outage window for each server, particularly for the live subscribers which will be done last.

I've been caught in the past by (a) an install that switched version even though I'd told it not to, and (b) one where the publisher refused to switch until the subscribers had been upgraded.

Thanks, Tony S

Roger Kallberg · ‎07-22-2020

I have never attempted to do a switch version prior to all nodes inactive partition being updated. Not sure if it would work for you. The upgrade to 12.x from prior versions will include the CVOS version to be upgraded to CentOS from RHEL, so it will involve multiple restarts prior to the inactive partition being on version 12.x. My recommendation would be to upgrade all nodes before you switch the CM publisher, TFTP, IMP publisher, backup CPE subs, IMP subscriber and last active CPE subs.

TONY SMITH · ‎07-23-2020

Thanks for the reply. My reason for preferring to switch version sooner rather than later in this particular case is so that we only have to arrange on downtime window for the upgrade of the live subscribers. Doing a separate switch we need downtime while those subscribers upgrade, then a second window when they switch version. Or a really long window.

A secondary reason is that the sooner the publisher comes up in the new version the sooner we know the upgrade is virtually certain to be successful. I have had upgrades that fail at the switch version stage, the switch fails and the server reverts to the old version. Better to find that out at the start of the process.

Reading the upgrade guide I must say I find it a little unclear, but it does appear that you can switch version automatically as part of the installation. However it doesn't qualify that in any way, so conceivably it might apply only to a single server cluster.