Troubleshooting Exchange Server 2010 DAG Backup Log Files do not Truncate

If you encounter warnings such as log truncation failed to complete or the database is unavailable for recovery upon completion of a backup performed on an Exchange 2010 database that is a member of a Database Availability Group (DAG), use the steps in this article to disable the Exchange Replica Writer, and then execute a new backup.

Determine Active and Passive Mailboxes

To determine if there are a combination of active and passive mailboxes,

1. Log in to the Exchange Server as the administrator, and open the event log.

2. In the log file, search for and view Event ID 2137, for example:
   Log Name: Application
   Source: MSExchangeRepl
   Date: 24/01/2014 11:25:00 AM
   Event ID: 2137
   Task Category: Service
   Level: Warning
   Keywords: Classic
   User: N/A
   Computer: EX01.exchangebbs.local
   Description:
   RPC request to the Microsoft Exchange Information Store service for log truncation failed for database Mailbox Database 02\EX01. Error: 3523092309

3. To determine where Mailbox Database 02 is mounted, at a command prompt, enter the following command:
   C:\>Get-MailboxDatabaseCopyStatus

4. Press Enter. The results displays the name, location, and status of the Mailbox Databases, for example:

   Name Status
   ---- ------
   Mailbox Database 01\EX01 Mounted
   Mailbox Database 02\EX01 Failed
   Archive Mailboxes\EX01 Mounted

5. In the above example, log truncation on Mailbox Database 02 failed because it is a passive database copy on server EX1 and is mounted on a different DAG member.

Disable Exchange Replica Writer

Use the following steps to disable Exchange Replica Writer,

1. On the Exchange Server, type regedit in the Start menu to open the Registry Editor.
2. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ExchangeServer\V14\Replay\Parameters
3. Add a DWORD entry EnableVSSWriter and set the value data to 0 (zero).
4. At a command prompt, enter the following command:
   C:\>Restart-Service MSExchangeRepl
5. Press Enter. The Microsoft Exchange Replication Service restarts.
6. The VSS Writer for Exchange 2010 Mailbox Database backups is now disabled.

Run the Backup Job

You can now log back in to the Barracuda Backup web interface and rerun the Exchange Server 2010 DAG backup from the Backup > Schedules page.