Exchange Database Mobility
Microsoft Exchange Server 2010 introduces a new technology for improved database availability and resilience. Exchange 2010 also no longer includes other database replication technologies that were part of Exchange 2007. These changes can have significant impact on the design of both customer storage solutions, and on how backup and restore applications interact with Exchange 2010.
Administrators configure Exchange DAGs using PowerShell commands. This topic does not describe everything needed to understand or implement Database Mobility in Exchange 2010. To learn more, you can find more information about High Availability and Site Resilience on TechNet.
For backup operations, if the Exchange 2010 databases being backed up are configured in a DAG, the backup application can better prevent interference between the snapshot and the active server’s performance by taking the snapshot on one of the inactive database copies. Because the database copies are for the most part synchronized, the backup application can take snapshots from different copies of the database, and later reconstruct it from the pieces.
For more information about backup up Exchange 2010 databases, read the Backup Operations section in this SDK.
In an Exchange 2010 Database Availability Group, the intent is to have multiple copies of the database on different machines. When one or more copies of the database are lost due to hardware or other system failure, information from the other copies can be used to reseed the database via normal replication operations.
The only supported method of restoring DAG databases from backed-up data is when all copies of the database are being restored using the same backup data. Because the database log files might be slightly different between the copies, restoring individual database copies using different data can lead to the database being unmountable.
For more detailed information about restoring a database configured in a DAG, read the Restoring a Database Availability Group Copy section in this SDK.