Managing Database Content Index State

From time to time the search indexes on Database copies in Exchange 2010 will become corrupt.  This will prevent the Activation Manager in the DAG from being able to "fail" the active database to that copy.
 
You can determine if any DB Copies have a Content Index State of failed by running the following cmdlet in the Exchange Management Shell:
 
Get-MailboxDatabase | Get-MailboxDatabaseCopyStatus|where { $_.contentindexstate -like "failed" }
If any copies report as having a failed Content Index State, they will need to be repaired.
 
Mounted Databases cannot be updated with the Update-MailboxDatabaseCopy cmdlet.  All copies reporting as failed can be updated with this cmdlet:
Get-MailboxDatabase | Get-MailboxDatabaseCopyStatus|where { ($_.contentindexstate -like "failed") -and ($_.status -ne
 "Mounted") }| Update-MailboxDatabaseCopy -CatalogOnly