Tape media rotation strategies
Many tape media rotation strategies exist that you can use to back up your data.
The most commonly used tape media rotation strategies include the following:
-
Son, which uses the same tape each day to run a full backup.
-
Father/Son, which uses multiple tapes, and includes a combination of weekly full and daily differential or incremental backups for a two-week schedule. This strategy provides backups for off-site storage .
-
Grandfather, which uses multiple tapes, and includes a combination of weekly and monthly full and daily differential or incremental backups. This strategy also provides backups for off-site storage.
Son media rotation strategy
The Son media rotation strategy requires the following:
Table: Son media rotation strategy
| Item | Description |
|---|---|
| Number of media required | 1 (minimum) |
| Overwrite protection period | Last backup |
The Son strategy involves performing a full backup every day.
Figure: Son backup strategy
Although the Son strategy is easy to administer, backing up with a single media is not an effective method of backup. Magnetic media eventually wears out after many uses and the data you can restore only spans back to your last backup.
Father/Son media rotation strategy
The Father/Son media rotation strategy requires the following:
Table: Father/Son media rotation strategy
| Item | Description |
|---|---|
| Number of media required | 6 (minimum) |
| Overwrite protection period | Two weeks |
The Father/Son media rotation strategy uses a combination of full and differential or incremental backups for a two-week schedule.
In the Father/Son scenario, four media are used Monday through Thursday for differential or incremental backups. The other two media containing full backups are rotated out and stored off-site every Friday.
The Father/Son strategy is easy to administer and lets you keep data longer than the Son strategy. The Father/Son strategy is not suitable for the stringent data protection needs of most network environments.
When this backup strategy is first implemented, you must start with a full backup.
Figure: Father/Son backup strategy
Grandfather media rotation strategy
The Grandfather media rotation strategy requires the following:
Table: Grandfather media rotation strategy
| Item | Description |
|---|---|
| Number of media required | 19 (minimum) |
| Overwrite protection period | One year |
The Grandfather method is one of the most common media rotation strategies. The Grandfather method is easy to administer and comprehensive enough to allow easy location of files when they need to be restored.
In the Grandfather scenario, four tapes are used Monday through Thursday for incremental or differential backups; another three tapes are used every Friday for full backups.
The remaining 12 media are used for monthly full backups and are kept off-site.
Figure: Grandfather backup strategy
The Grandfather strategy is recommended because it offers a good media number to storage life ratio (19 media/1 year). You can easily incorporate more media. For example, you can perform a full backup on the last Saturday of the month to keep permanently.
Related information