Application Data Synchronization

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Applies To: System Center Data Protection Manager 2007

Protection of application data is new in DPM 2007.

For application data, after the replica is created, the protection agent tracks changes to volume blocks that belong to application files.

How changes are transferred to the DPM server depends on the application and the type of synchronization. The operation that is labeled synchronization in DPM Administrator Console is analogous to an incremental backup, and it creates an accurate reflection of the application data when it is combined with the replica.

During the type of synchronization that is labeled express full backup in DPM Administrator Console, a full Volume Shadow Copy Service (VSS) snapshot is created, but only blocks that have changed since the last express full backup are transferred to the DPM server and used to create the new express full backup.

Each express full backup creates a recovery point for application data. If the application supports incremental backups, each synchronization also creates a recovery point. Both express full backup and incremental synchronizations are labeled Recovery point creation on the Jobs tab. The synchronization type that is supported by each type of application data is summarized in the following list:

  • For protected Exchange data, synchronization transfers an incremental VSS snapshot by using the Exchange VSS writer. Recovery points are created for each synchronization and express full backup.

  • SQL Server databases that are log-shipped, that are in read-only mode, or that use the simple recovery model do not support incremental backup. Recovery points are created only for each express full backup. For all other SQL Server databases, synchronization transfers a transaction log backup, and recovery points are created for each incremental synchronization and express full backup. The transaction log is a serial record of all the transactions that have been performed against the database since the transaction log was last backed up.

  • Windows SharePoint Services and Microsoft Virtual Server do not support incremental backup. Recovery points are created only for each express full backup.

  • System state protection uses only express full backup.

Incremental synchronizations require less time than performing an express full backup. However, the time required to recover data increases as the number of synchronizations increases. This is because DPM must restore the last full backup and then restore and apply all the incremental synchronizations up to the point in time that is selected for recovery.

To enable faster recovery time, DPM regularly performs an express full backup, a type of synchronization that updates the replica to include the changed blocks.

During the express full backup, DPM takes a snapshot of the replica before updating the replica with the changed blocks. To enable more frequent recovery points and to reduce the data loss window, DPM also performs incremental synchronizations in the time between two express full backups.

As with the protection of file data, if a replica becomes inconsistent with its data sources, DPM generates an alert that specifies which server and which data sources are affected. To resolve the problem, the administrator repairs the replica by initiating a synchronization with consistency check on the replica. During a consistency check, DPM performs a block-by-block verification and repairs the replica to make it consistent with the data sources.

You can schedule a daily consistency check for protection groups, or you can initiate a consistency check manually.