System Administration Guide: Basic Administration

Tape Requirements for the Daily Cumulative, Weekly Cumulative Schedule

With this schedule, you need six tapes if you want to reuse daily tapes, or nine tapes if you want to use four different daily tapes: one tape for the level 0, four tapes for Fridays, and one or four daily tapes.

If you need to restore a complete file system, you need the following tapes: the level 0, the most recent Friday tape, and the most recent daily tape since the last Friday tape, if any.