Tower of Hanoi
The Tower of Hanoi rotation scheme is based on the mathematical game that bears the same name. In this schedule, one media set "A" is used every other backup session (daily sessions in this example).
Start Day 1 with 'A' and repeat every other backup (every other day).
The next media set 'B' starts on the first non-'A' backup day and repeats every fourth backup session.
Media set 'C' starts on the first non- 'A' or non-'B' backup day and repeats every eighth session.
Media set 'D' starts on the first non-'A', 'B', or 'C' backup day and repeats every sixteenth session.
Media set 'E' alternates with media set 'D'.
The advantage to the Tower of Hanoi scheme is that with each new media set added to the rotation, the backup history doubles. The frequently used media sets have the most recent copies of a file, whereas less frequently used media retain older versions.
This backup scheme can be difficult to keep track of manually and therefore is generally done with the help of rotation schemes provided in backup software packages.
As with the Grandfather-Father-Son rotation scheme, tapes should be periodically removed from the rotation for archive purposes.