Update a FailedAndSuspended mailbox database copy in Exchange Server

When we are dealing with Exchange server DAG you may encounter issues with database copies. The cause in most cases will be storage related, though there could be other reasons as well.
The following command shows you the database copies health.

Get-MailboxDatabaseCopyStatus *

Before going to the next step of fixing the failed database copy ensure there is no issue with the drive/storage.

For example, database drive failure/RAID failure or RAID rebuilding at the time of failure.

Reseed the database using the following commands:

First, suspend the failed database copy.

Suspend-MailboxDatabaseCopy MailboxDatabase-01\MBX04

Then update the database with DeleteExistingFiles switch. If the server still have the old files will delete the files in the destination and seed again from scratch.

Update-MailboxDatabaseCopy MailboxDatabase-01\MBX04 -DeleteExistingFiles

By default, it will reseed from the active server. If your active server is at a remote location and if you have another database copy in the same site, it is better to seed from the nearby server by using the SourceServer switch. The following command will be used as per the above databases:

Update-MailboxDatabaseCopy MailboxDatabase-01\MBX04 -SourceServer MBX0 -DeleteExistingFiles

The time to update the database copy will depend on the size of the database.
Once the database is updated, run the same command you ran above to check the database copy status. i.e. the following command. You can see your database copy is reseeded and healthy:

Get-MailboxDatabaseCopyStatus *

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