Care needs to be taken when rebooting Exchange DAG Members. Rebooting an Exchange server that is in a DAG requires switching the active database to the member not being rebooted.
0) Check that all DB’s are healthy and check which servers is currently the active server. Run the following from Exchange Management Shell:
— At this point if you find there is an Exchange server with no active databases, it is considered a Passive DAG Member and you can reboot it at this point.
1) Perform “server Switchover” to change the active databases away from the server you want to reboot to a DAG member that is not being rebooted: Move-ActiveMailboxDatabase –Server ExchangeServerYouAreRebooting
Before and after each switchover make sure the DB’s are healthy and verify which server is the active server:
Note: After a reboot it can take a few minutes for the databases to return to a Healthy state.
Note: The output of “Get-MailboxDatabaseCopyStatus” may return Index errors, this is not a mission critical error. Here are steps to troubleshoot Exchange content index errors.
2) Reboot the Exchange server that no longer has active databases on it
3) Once the first server from step 2 is rebooted and back online and you have checked the db replication health (Get-MailboxDatabaseCopyStatus *), repeat the steps 1 and 2 for the next Exchange DAG member you’d like to reboot.
Note: Avoid having more that one Exchange DAG member offline at a time.