The dump level you specify in the ufsdump command (0-9) determines which files are backed up. Specifying dump level 0 creates a full backup. Numbers 1-9 are used to schedule incremental backups, but have no defined meanings. Numbers 1-9 are just a range of numbers 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.
Doing daily, cumulative incremental backups is the most commonly used backup scheme and is recommended for most situations. The following example shows a schedule using a level 9 dump each day, and a level 5 dump on Friday to restart the process.
In the following 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.
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.
In the following 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.