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 1		3	4	5	6	2
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 using the previous schedule. Each letter represents a different file.

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	hi	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 (if you want to reuse daily tapes--not recommended), or 21 tapes (if you save weekly tapes for a month): one for the level 0, four for the Fridays, and four or 16 daily tapes.

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