Differential Backups

A differential backup contains only the data that is new or has changed since the last full backup. Like incremental backups, differential backups, on average, consume less media and place less of a burden on resources than full backups. Differential backups are cumulative. This means that each differential backup contains all changes accumulated since the last full backup. Each successive differential backup contains all the changes from the previous differential backup. 

The illustration on the right demonstrates the nature of differential backups. For simplicity, assume there is a file system that contains six files as represented in the figure.

Backup #1 is a full backup and therefore writes all the data to the backup media. Backups #2 through #n-1 are differential backups and only back up those files that changed since the time of the last full backup. For example, files A, B, and E changed after the full backup and were therefore backed up in Backup #2 as well as all subsequent differential backups. File C changed sometime after Backup #2 and was consequently backed up in Backup #3 and all subsequent differential backups. File F did not change; hence, it was not backed up in any of the differential backups, but it was included in both full backups, which, by definition, back up everything.


  1. From the CommCell Console, navigate to Client Computers > virtualization_client > Virtual Server > VMware > backup_set.
  2. Right-click the subclient and click Backup.
  3. From the Backup Options dialog box, select from the following options:

    Backup Type:

    • Select Differential.

    Backup Schedule:

    • Select Run Immediately
  4. Click OK.
  5. You can track the progress of the backup job from the Job Controller window.
  6. When the backup has completed, the Job Controller displays Completed.

Last modified: 2/6/2018 8:38:53 PM