The cmdlet will allow you to avoid your Exchange getting into a Split-BrainSyndrome.
This example suspends replication and replay activity for the copy of a database named DB1 that’s hosted on a Mailbox server named MBX3. An optional administrative reason for the suspension is also specified.
Suspend-MailboxDatabaseCopy -Identity DB1MBX3 -SuspendComment "Maintenance on MBX3"
This example only activation for the copy of a database named DB3 that’s hosted on a Mailbox server named MBX2.
Suspend-MailboxDatabaseCopy -Identity DB3MBX2 -ActivationOnly