Ovo se odnosi na sigurnosnu kopiju podataka.

http://www.1o1.com/pdf/Linux/sigurnosna_pohrana_podataka.pdf

Postoje dvije razine pohrane promijenjenih datoteke: spremanje onih datoteka koje su
promijenjene u odnosu na prethodnu potpunu ili na posljednju djelomi~nu pohranu. Sigurnosnu
pohranu podataka mo`ete zamisliti u tri razine:
Razina 0: Potpuna pohrana podataka
Razina 1: Pohrana datoteka koje su promijenjene u odnosu
zadnju potpunu pohranu
Razina 2: Pohrana datoteka koje su promijenjene u odnosu
zadnju pohranu razine 1

Grandfather = Full backups
Father = Incremental backups
Son = Differential backups

Grandfather-father-son backup refers to the most common rotation scheme for rotating backup media. Originally designed for tape back up, it works well for any hierarchical backup strategy. The basic method is to define three sets of backups, such as daily, weekly and monthly. The daily, or son, backups are rotated on a daily basis with one graduating to father status each week. The weekly or father backups are rotated on a weekly basis with one graduating to grandfather status each month. Often one or more of the graduated backups is removed from the site for safekeeping and disaster recovery purposes.