Grandfather, Father, Son definition operating system
(GFS) A backup rotation
scheme in which a "grandfather" backup is performed on the first Monday of each month, a "father" backup is performed on every other Monday and a "son" backup is performed on every other day of the week. Grandfather tapes are kept for a year, father tapes for a month and son tapes for a week. The exact schedule (and thus the number of tapes required) may vary, as may the choice of full backup or incremental backup
, but the idea is that it should be possible to restore versions of any file of different ages: e.g. yesterday's, last week's or last year's version.