VSS backup using Windows Server Backup on Exchange Server 2007 SP2 fails when LCR or SCR is enabled
Exchange 2007 Service Pack 2 introduces the ability to take Exchange-aware, VSS backups on Windows Server 2008. This is via a plug-in to the Windows Server Backup tool that is native to the operating system. For those who are not aware of this functionality, you can read more about it here:
Using Windows Server Backup to Back Up and Restore Exchange Data
Notice the last bullet point on this page, though:
"The plug-in does not support the Exchange Replica VSS Writer that is part of the Replication service. As a result, you cannot use Windows Server Backup to backup passive copies of storage groups."
Your first thought in reading this may be simply that you cannot backup the passive node of a Cluster Continuous Replication (CCR) cluster with Windows Server Backup. However, this also applies to standalone servers that are Standby Continuous Replication (SCR) targets or that have Local Continuous Replication (LCR) enabled. When Windows Server Backup processes a backup of a server with LCR or SCR enabled, it calls the VSS Writer from the Replication service instead of the VSS Writer from the Information Store service. Since Windows Server Backup was not designed or tested for use with the Replication Service, the Exchange-aware portion of the backup fails.
The backup will complete, but you will see this error in the status window of the backup job:
The following error event will be logged in the Application Log:
Log Name: Application
Date: 10/14/2009 8:44:53 AM
Event ID: 565
Task Category: None
Consistency check for component '1a0a0e79-76ce-4985-aa99-35f5018b0ed7'\'Microsoft Exchange Server\Microsoft Information Store\SERVER1' failed. Application 'Exchange' will not be avaliable in the backup done at time '10/14/2009 8:44:42 AM'
In order to take an online Exchange-aware backup of a server using LCR or serving as an SCR target you must disable the Replica VSS Writer used by LCR. To do so, follow these steps:
1. Open Registry Editor and browse to the HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Replay\Parameters registry key.
2. Add a new DWORD value named EnableVSSWriter and set the value to 0 (zero).
3. Restart the Microsoft Exchange Replication Service.
This will allow Windows Server Backup to use the Microsoft Exchange Information Store service's VSS Writer to perform the backup. You can confirm that the backup was successful by starting the Recovery Wizard in Windows Server Backup and verifying that you are able to select the Exchange application for recovery.