I?ve been installing a CCR cluster this week and thought it might be worth posting up here how to patch it!
Older version of Exchange clusters were a little annoying to patch, but this is really simple!
Basically make sure a node is completely passive (i.e. move the CMS and the cluster group)
Move-ClusteredMailboxServer NameofCMS ?TargetMachine NameofTargetNode ?MoveComment Patching ?Comfirm:$false
Cluster Group ?Cluster Group? /move
Then on the node which is now completely passive, install the patch.
You can then move everything back to the newly updated node and repeat on the other node.
One thing to note, if a storage group for any clustered mailbox server is enabled for SCR, you should apply the update rollup first to the SCR target computers. After all SCR target computers have been updated, the clustered mailbox server (which is also the SCR source) can be updated.
For more info see the link below: