Use Setup /m:RecoverServer to recover a server
Important: In this example we are recovering DAG member MBX1 which has only one database copy DB1.
You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Mailbox database copies" entry in the High Availability Permissions topic.
1. Retrieve any replay lag or truncation lag settings for any mailbox database copies that exist on the server being recovered by using the Get-MailboxDatabase cmdlet.
2. Remove any mailbox database copies that exist on the server being recovered by using the Remove-MailboxDatabaseCopy cmdlet.
3. Remove the failed server's configuration from the DAG by using the Remove-DatabaseAvailabilityGroupServer cmdlet.
Note: If the DAG member being removed is offline and cannot be brought online, you must add the ConfigurationOnly parameter to the above command.
1. Reset the server's computer account in Active Directory. For detailed steps, see Reset a Computer Account.
2. Open a Command Prompt window. Using the original Setup media, run the following command.
3. When the Setup recovery process is complete, add the recovered server to the DAG by using the Add-DatabaseAvailabilityGroupServer cmdlet.
4. After the server has been added back to the DAG, you can reconfigure mailbox database copies by using the Add-MailboxDatabaseCopy cmdlet. If any of the database copies being added previously had replay lag or truncation lag times greater than 0, you can use the ReplayLagTime and TruncationLagTime parameters of the Add-MailboxDatabaseCopy cmdlet to reconfigure those settings.