Grandfather-Father-Son (GFS) Tape Rotation
This is a very common scheme used as a hierarchical data retention strategy.
For example, three sets of backups, such as weekly, monthly and yearly are defined. You can vary this frequency to suit the requirements of your environment. The weekly or Son backups are rotated on a weekly basis with one graduating to Father status each month. The monthly or Father backups are rotated on a yearly basis with one graduating to Grandfather status each year. One or more of the graduated backups is removed from the site for disaster recovery and archival purposes.
There are two ways in which this can be accomplished.
Using Selective Copies
- Perform incremental backups daily and full backup weekly to the primary copy (Retention can be set to 30 days)
- Create a selective copy for the monthly full backups (Retention can be set to 365 days)
- Create another selective copy for the yearly full backups (Retention can be set to infinite)
This method creates separate copies of data which may be useful for off-site storage requirements.
Using Extended Retention Rules on the Primary Copy
- Set the basic retention rules on the primary copy to 30 days
- In addition set extended retention rules for monthly full backups to 365 days and yearly full backups as infinite as shown in the sample image.
This method carves out a graded retention from a single copy.
Refer to Extended Retention Rules for more information.
In reality, a combination of both these methods may be required. For example, only one selective copy may be created and extended retention established in this selective copy.
In addition, you can manually retain specific jobs for a longer period (in addition to the retention period specified in the copy) if there is a necessity to retain specific jobs. Refer Retain a Job in the Copy for more information.