Tape Requirements for the Daily Cumulative, Weekly Cumulative Schedule

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

• The most recent Friday tape

• The most recent daily tape since the last Friday tape, if any

Example--Daily Cumulative, Weekly Incremental Backups

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 46-9 Daily Cumulative, Weekly Incremental Backup Schedule

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 46-10 Contents of Tapes for Daily Cumulative, Weekly Incremental Backup Schedule

Tape Requirements for the Daily Cumulative, Weekly Incremental Backup Schedule

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

Example--Daily Incremental, Weekly Cumulative Backups

The following table shows a schedule where each weekday tape contains only the files that changed since the previous day. In addition, each Friday's tape contains all files changed since the initial level 0 backup at the beginning of the month.

Table 46-11 Daily Incremental, Weekly Cumulative Backup Schedule

The following table shows how the contents of the tapes can change across two weeks with the daily incremental, weekly cumulative schedule. Each letter represents a different file.

Table 46-12 Contents of Tapes for Daily Incremental, Weekly Cumulative Backup Schedule

Tape Requirements for Daily Incremental, Weekly Cumulative Schedule

With this schedule, you need at least 9 tapes if you want to reuse daily tapes, which is not recommended. Preferably, you need 21 tapes if you save weekly tapes for a month: one tape for the level 0, four tapes for the Fridays, and four or 16 daily tapes.

• 1 tape for the level 0 backup.

• 4 tapes for all the Friday backups.

• 4 or 16 daily tapes.

If you need to restore the complete file system, you need the following tapes:

• The level 0 tape.

• The most recent Friday tape.

• All the daily tapes since the last Friday tape, if any.