Optimizing Deduplication Percentage on Storage Policy Copy

By default, the deduplication percentage is low on the storage policy copy compared to the percentage on the primary copy, because multiple streams are used for high-speed data transfer. However, you can configure a storage policy copy with deduplication to achieve an optimized deduplication percentage during auxiliary copy operations. The benefits of configuring the feature are:

  • The auxiliary copy operation achieves a higher deduplication percentage by first copying full backups or synthetic full backups, followed by incremental backups or differential backups as the possibility of same data getting auxiliary copied through multiple streams is reduced.

    Note: If there is an error in copying a full backup, then the system makes three attempts to copy the full backup. After the third failure, that particular full backup is skipped from the copying process and the next backup job is selected for copying. In case, the next job is not a full backup, then the system picks up the next available incremental or differential backup without the full backup being fully copied.

  • In scenarios where the data keeps changing and the incremental backups are quiet large, using the Space optimized Auxiliary Copy option helps in reducing the duplicate signature on the deduplication database (DDB) and also the space on the DDB disk.
  • Configuring this feature helps in keeping the ddb size of the secondary copy close to that of source copy when identical job exists on both copies.

For example, in your CommCell environment, you have scheduled full backups or synthetic full backups to run weekly and incremental backups to run daily. If you enable the space optimization option, then during auxiliary copy operation the full backups or the synthetic full backups are copied first in a sequence and then all the incremental backups are copied. This method achieves a higher deduplication percentage on the storage policy copy.

Before You Begin

To optimize the deduplication percentage on storage policy copies by using the Space optimized Auxiliary Copy option, you must ensure that the Use Scalable Resource Allocation option is selected on the General tab of the Auxiliary Copy Job Options dialog box. For more information on Use Scalable Resource Allocation option, see Performing an Auxiliary Copy Operation.


  1. From the CommCell Browser, expand Policies > Storage Policies.
  2. Right-click appropriate storage policy, point to All Tasks, and then click Create New Copy.
  3. In the Copy Properties dialog box, specify the appropriate settings.

    For details, see Copy Properties - General.

  4. In the General tab, select the Enable Deduplication check box.
  5. Click the Copy Policy tab, and verify that the Space optimized Auxiliary Copy check box under Copy Configuration is selected.
  6. Click OK.

Last modified: 1/3/2020 7:51:20 PM