(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.