Explanation
Grandfather-father-son (GFS) is a common backup rotation scheme that uses daily, weekly, and monthly backup media in a first-in, first-out (FIFO) method. The daily backups are rotated on a 3-months basis using a FIFO system as above. The weekly backups are similarly rotated on a bi-yearly basis, and the monthly backups are rotated on an annual basis. The oldest backup media in each cycle are overwritten by the newest ones. This scheme provides multiple versions of backup data at different intervals, allowing for flexible restoration options. Waterfall is another name for GFS. Synthetic full is a backup method that combines an initial full backup with subsequent incremental backups to create a new full backup without transferring all data again. Tower of Hanoi isanother backup rotation scheme that uses an algorithm based on moving disks between three pegs. References:
https://en.wikipedia.org/wiki/Backup_rotation_scheme