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. A lower dump number always restarts a full or a cumulative backup. The following examples show the flexibility of the incremental dump procedure using levels 1–9.

Example—Dump Levels for Daily, Cumulative Backups

Doing daily, cumulative incremental backups is the most commonly used backup schedule and is recommended for most situations. The following example shows a schedule that uses a level 9 dump Monday through Thursday, and a level 5 dump on Friday restarts process.

Figure 23–1 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 using the same number Monday through Thursday, with any lower number on Friday. For example, you could have specified levels 4, 4, 4, 4, 2 or 7, 7, 7, 7, 5.

Example—Dump Levels for Daily, Incremental Backups

The following example shows a schedule where you capture only a day's work on different tapes. This type of backup is referred to as a daily, incremental backup. In this case, sequential dump level numbers are used during the week (3, 4, 5, 6) with a lower number (2) on Friday. The lower number on Friday restarts the processing.

Figure 23–2 Incremental Backup: Daily Incremental

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 specified sequence, as described in the examples.