The procedure to upgrade a management server is simple. You start with upgrade on your primary management server using CPUSE or advanced method according target version. When you upgraded the primary management server, open SmartConsole and push a install database only primary management server and you must to install policy on gateways to validate and reestablish connectivity between gateways and primary management server on TCP/257 port (Log).
Once a completed the steps above, you must perform a fresh install of secondary management server using .iso image or CPUSE package and when completed the "First Wizard", reestablish SIC with primary management server. Then, perform a install database on both management servers.
When you started the installation of database on both machines, a full sync process will be initiate to "copy" objects from primary management server to secondary management server.
Ah, don't forget validate logs! (:
I hope I helped you.