Endpoint Protection

We just upgraded our passive SEPM node to 12.1.5 as we are having GUP issues.

What are the proper steps to fail over to the updated passive node so we can confirm it is functioning properly before upgrading the primary node?

You would need to stop the SEPM service.

Just make sure you configure your management server list correctly. Both SEPMs needs to be listed and you can set each with a Priority 1 or 2. Once you stop the service, clients should go to the next SEPM in the MSL.

Configuring a management server list

Managed Load Balancing: Setting up Management Server Lists based on locations in Symantec Endpoint Protection Manager.

Setup the MSL.. So that after you stop the SEPM service, the clients would start communicating witht the othe SEPM. 

http://www.symantec.com/docs/TECH103175

To clarify, the SEPM services must be stopped on ALL SEPMs in the same site (i.e. sharing the same DB) prior to the upgrade anyway.

This means that after the upgrade of your passive SEPM to RU5, it should be the only one with running services, and therefore the only one clients can connect to.  This means just logging into it should show you whether or not things are working.

If all's cool, shut down the services on the passive SEPM (so that, again, services are stopped on all SEPMs) and upgrade the primary.  Once done, log in and check if clients are checking in, the startup the services on the passive SEPM (as they'll both be on the same version at this point).

Replicating SEPM environments are slightly different.  Can you provide more info on the estate you're upgrading?