Using the Grandfather-Father-Son tape rotation scheme

Tape rotation for the GFS backup scheme is substantially defined by the tape options specified for the backup policy/plan to be created.

Assume the GFS settings are the following:

• Start backup at: 11:00:00 PM
• Back up on: Workdays
• Weekly/Monthly: Friday
• Keep backups: Daily: 2 weeks; Weekly: 2 months; Monthly: 1 year.

The main goal is to achieve full automation of tape rotation for these settings.

Keep in mind that a monthly backup is full, a weekly backup is differential, and a daily backup is incremental in this implementation of the GFS scheme. The first backup is always full. So if the backup policy/plan starts on Wednesday and full backups should be created on every fourth Friday, on Wednesday the first backup will be full instead of an incremental one.

There are analyzed examples showing how the GFS scheme can be combined with different tape options in the following sections:

• GFS Example 1. The Use a separate tape set option is selected. All the Always use a free tape options are cleared. It requires 25 tapes in rotation.
• GFS Example 2. The Use a separate tape set option is selected. The Always use a free tape: For each full backup option is selected. Other Always use a free tape options are cleared. It requires 16 tapes in rotation.
• GFS Example 3. The Use a separate tape set option is selected. All the Always use a free tape options are selected. It requires 28 tapes in rotation.

These examples demonstrate how the number of tapes required for automated rotation depends on the tape options. If a tape library does not have enough tapes for automated rotation, the Tasks Need Interaction window will sometimes ask you to load a free tape into the library.