Grandfather-father-son backup scheme

Grandfather-father-son backup is a common rotation scheme for backup media, in which there are three or more backup cycles, such as hourly, daily, weekly and monthly.

This scheme allows you to express backup schemes like the following:

• Create a backup every hour, stored for 24 hours.
• Create a backup every day, stored for 7 days.
• Create a backup every week, stored for 4 weeks.
• Create a backup every month, stored for 12 months.

This scheme is especially powerful with backup solutions that rely on storing data in chunks, where every snapshot only stores new chunks for changed data, and where every snapshot may be deleted (or “pruned”) independently of the others.