As a best practice always prior installing updates and doing changes we can use a useful Microsoft script that is included on our exchange suite
1. Log into the dag server that will be put in maintenance; navigate to the script folder, by default under “C:\Program Files\Microsoft\Exchange Server\V14\Scripts”
This will perform:
Move all the active databases off of the server
Set the “DatabaseCopyAutoActivationPolicy” to Blocked on the mailbox server, thus it will block databases from moving to that server;
make sure all critical DAG support functionality (for example, the Primary Active Manager PAM role) that might be on the server is moved to another server, and blocked from moving back to the server.
2. Use script “StartDagServerMaintenance” to put the DAG member server into maintenance mode:
.\StartDagServerMaintenance.ps1 –serverName “NODE”
3.Ensure that the node has no active copies working prior doing changes & check cluster status as paused
4. Do the changes
5. Put the node back online and tune up database active copies as it was before
use the “StopDagServerMaintenance” scripts which also reside in the scripts folder to stop maintenance mode on DAG Node
5.Navigate to the script folder again , by default under “C:\Program Files\Microsoft\Exchange Server\V14\Scripts”:
.\StopDagServerMaintenance.ps1 -serverName “NODE”
6. Happy patching !