Level

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Amanda backs up each DLE at a specific level, as determined by the planner. Generally, levels describe full or incremental backups, but other software uses those terms differently.

In Amanda, a level-0 backup is a full dump: all data from the DLE is backed up, and a recovery from this dump will get all of that data back.

A level-1 backup is a dump only of data that has changed since the most recent level 0. To recover the entire DLE, you'll need both the level 1 and level 0 dumps. Level-1 backups are generally smaller than level-0 backups.

A level-2 backup is a dump only of data that has changed since the most recent level 1. In general, a level N backup is a dump only of data that has changed since the most recent level N-1 backup.

As an example, assume you have only the following backups:

A: level-3 -- April 6
B: level-0 -- April 7
C: level-1 -- April 8
D: level-1 -- April 9
E: level-2 -- April 10
F: level-1 -- April 11
G: level-0 -- April 12

A recovery to the state on the 12th would only require dump G.

A recovery to the state on the 11th would require first dump B and then dump F. Note that C and D are not required.

A recovery to the state on the 10th would require first dump B, then dump D, then dump E.

A full recovery of the state on the 6th is impossible, since the level 0, 1, and 2 dumps on which it is based are gone.

Note that, in general, recoveries require the most recent level 0, 1, .. N-1, N dumps.


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