Example--Daily Incremental, Weekly Cumulative Backups

Table 33-11 shows a schedule where each weekday tape contains only the files changed since the previous day, and each Friday's tape contains all files changed since the initial level 0 at the beginning of the month.

Table 33-11 Daily Incremental/Weekly Cumulative Backup Schedule

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

Table 33-12 shows how the contents of the tapes can change across two weeks.

Table 33-12 Contents of Tapes for Daily/Weekly Cumulative Backup Schedule

	Mon	Tues	Wed	Thurs	Fri
Week 1	a b	c d	e f g	h	a b c d e f g h i
Week 2	j k l	m	n o	p q	a b c d e f g h i j k l m n o p q r s

Tape Needs

With this schedule you will need at least nine tapes: one for the level 0, four for the Fridays, and four daily tapes, assuming you reuse daily tapes each week, which is not recommended. If you save the weekly tapes for a month, you need 21 tapes.

If you need to restore the complete file system, you need six tapes: the level 0, the most recent Friday tape, and all the daily tapes for that week.