The following table shows a schedule where each weekday tape accumulates all files that changed since the beginning of the week, or the initial level 0 backup for the first week. In addition, each Friday's tape contains all the files that changed that week.
Table 22–9 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 following table shows how the contents of the tapes can change across two weeks with the daily cumulative, weekly incremental backup schedule. Each letter represents a different file.
Table 22–10 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 |
With this schedule, you need six tapes if you want to reuse daily tapes. However, you need nine tapes if you want to use four different daily tapes:
One tape for the level 0 backup
Four tapes for Fridays
One or four daily tapes
If you need to restore a complete file system, you need the following tapes:
The level 0 tape
All the Friday tapes
The most recent daily tape since the last Friday tape, if any