Using Dump Levels to Create Incremental Backups

The dump level you specify in the ufsdump command (0-9) determines which files are backed up. Dump level 0 creates a full backup. Levels 1–9 are used to schedule incremental backups, but have no defined meanings. Levels 1–9 are just a range of numbers that are used to schedule cumulative or discrete backups. The only meaning levels 1–9 have is in relationship to each other, as a higher or lower number.

The following examples show the flexibility of the incremental dump procedure using levels 1–9.

Dump Levels for Daily, Cumulative Backups

Doing daily, cumulative incremental backups is the most commonly used backup scheme and is recommended for most situations. The following example shows a schedule that uses a level 9 dump each day, and a level 5 dump on Friday to restart the process.

Figure 46–1 Incremental Backup: Daily Cumulative

In the preceding example, you could have used other numbers in the 1–9 range to produce the same results. The key is having the same number each day, with any lower number on Friday. For example, you could have specified levels 4, 4, 4, 4, 2 or 7, 7, 7, 7, 5.

Dump Levels for Daily, Discrete Backups

The following example shows a schedule where you capture only a day's work on different tapes. In this case, sequential dump level numbers are used during the week (3,4,5,6) with a lower number (2) on Friday.

Figure 46–2 Incremental Backup: Daily Discrete

In the preceding example, you could have used the sequence 6, 7, 8, 9 followed by 2, or 5, 6, 7, 8 followed by 3. Remember, the numbers themselves have no defined meaning. You attribute meaning by ordering them in a high/low sequence.