Policy Considerations and Synthetic Backups
Selecting the Synthetic Backup Option
The Synthetic Backup option is available under the following conditions:
- The policy type must be either Standard or MS-Windows-NT.
- The Collect True Image Restore Information With Move Detection option must be selected on the Policy Attributes tab.
- The schedule created for a synthetic backup must have the Synthetic Backup option selected.
- The master servers, media servers, and clients must all have NetBackup version 5.0 installed in order to synthesize backups.
- Generally, a tape library with multiple drives for reading and writing is needed, though not required.
- NetBackup must be configured to use the binary catalog format from NetBackup version 5.0. Backup images using the ASCII catalog format cannot be synthesized.
Schedules to Include in a Policy for Synthetic Backups
A policy for synthetic backups must contain at least three types of schedules:
- One schedule for a full, non-synthesized backup.
The traditional, full backup schedule must run successfully before the synthetic full backup schedule. The synthetic backup job will fail for a policy that contains a full synthetic backup schedule, but does not contain a traditional full backup schedule.
- Schedule(s) for incremental backups.
Incremental backups are necessary to capture the changes in the file system since the last full or incremental backup. The synthetic backup job will fail for a policy that contains full or incremental synthetic backup schedules and a traditional full backup schedule, but no incremental backup schedules.
Remember that since the synthetic backup synthesizes all of the incremental backups to create a new full or cumulative backup image, the synthetic backup is only as current as the last incremental backup.
Note
If you are configuring a synthetic cumulative backup and the clients are archive bit-based (default), use only differential incremental backups for the traditional, non-synthesized backups.
- One full and/or one cumulative backup schedule with the Synthetic Backup option selected.
Only one full and/or one cumulative schedule per policy is allowed to have the Synthetic Backup option selected. Even if multiple streams and clients are specified in the policy, only one synthetic job will run at a time for the policy. This prevents more than one job from starting at the same time and competing for the same resource.
Adding Clients to a Policy for Synthetic Backups
Every time a client is added to a policy that will be used for synthetic backups, the client must have a traditional, full backup created for it before a synthetic backup is possible. Upon adding a client to the policy, you must run a manual traditional full backup.
Since Collect True Image Restoration (TIR) with Move Detection is required for synthetic backups, all clients included in the policy must support TIR.
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