Performance of Deduplication Database (DDB) backup is slow on Windows MediaAgents

Article ID: DD0060 Troubleshoot performance issues during DDB backup by completing basic operations


Deduplication database backup performance decreases on Windows MediaAgents.


The performance of the DDB backup can decrease significantly for various reasons, such as:

  • A large number of concurrent I/O requests to the DDB volume.
  • When a DDB backup is run, a snapshot (shadow copy) of a DDB is created by using VSS on the same DDB volume. The shadow copy is deleted after the DDB data is backed up.

If the shadow copy storage is on the DDB volume during the DDB backup process, it might slow DDB backup performance.



To improve the DDB backup performance, complete each task until performance is optimized.

  • Relocate the shadow copy storage to a different volume (other than the DDB volume) on the computer. For instructions, see Move the volume shadow copy storage area to a different volume.
  • On the DDB Backup subclient, modify the Application Read Size to 256 KB.
    1. From the CommCell Browser, expand Client Computers > MediaAgent_client > defaultBackupSet.
    2. Right-click the DDBBackup subclient, and then click Properties.
    3. In the Subclient Properties of DDBBackup dialog box, on the Storage Device tab, click the Data Transfer Option tab.
    4. Select the Application Read Size check box, and then type or select the 256 KB.
    5. Click OK.
  • For slow disk I/O, enable the disk write caching on the DDB disk. For instructions, see Microsoft KB Article 324805.
  • Relocate the DDB to a storage that meets the requirements referenced in Deduplication Building Block Guide.
    For instructions, see Changing the Deduplication Database Location.