Synthetic Full Backup

Optimizing Synthetic Full Backups in Deduplication Appliances

Synthetic full backup operations back up all the data which are recently added or modified and writes a new baseline of items as a new job. This allows prior jobs to be aged, and then the new incremental backups are performed with this baseline as the reference.

Performance of a deduplication appliance such as Data Domain Array is bound by stream or thread performance. The synthetic full operation requires a concurrent read/write operation, which can affect the performance of the device.

It is recommended that you take the following steps to optimize the performance of the device:

  • Stagger your backup schedule in such a way that the minimum number of active streams are targeted to the device.
  • Alternately, if the synthetic full operation takes too long to complete, you can perform a Full backup followed by daily incremental backup jobs.
  • In cases where longer backup cycles are performed in the device, the backup performance may degrade over time. This may not be due to the concurrent read/write synthetic full jobs, instead it may be due to the large volume of deduplicated data on the deduplication appliance.

Recommendations for Tape Media

When using tape libraries with Synthetic Full backups the following is recommended:

  • Make sure to keep at least two media drives available for the same storage policy when the job starts. When tape Media is in use synthetic full backups will not work for subclients where the storage policy is associated with a stand-alone drive.

    This is because data is read and written simultaneously. Synthetic full backup reads data from one media and simultaneously write (restore) the result to the new active media within the same media group.

  • Have only one synthetic full job running to the tape drive for synthetic full backups with multiple streams where, the number of streams is more than the number of drives on the tape.