Example--Daily Cumulative, Weekly Incremental Backups

The table below shows a schedule where each weekday tape accumulates all files that changed since the beginning of the week (or the initial level 0 for the first week), and each Friday's tape contains all the files changed that week.

Table 42-9 Daily Cumulative/Weekly Incremental Backup Schedule

	Floating	Mon	Tues	Wed	Thurs	Fri
1st of Month	0
Week 1		9	9	9	9	3
Week 2		9	9	9	9	4
Week 3		9	9	9	9	5
Week 4		9	9	9	9	6

The table below shows how the contents of the tapes can change across two weeks using the previous schedule. Each letter represents a different file.

Table 42-10 Contents of Tapes for Daily Cumulative/Weekly Incremental Backup Schedule

	Mon	Tues	Wed	Thurs	Fri
Week 1	a b	a b c	a b c d	a b c d e	a b c d e f
Week 2	g	g h	g h i	g h i j	g h i j k

Tape Requirements

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 for the level 0, four for the Fridays, and one or four daily tapes.

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