what is the meaning ol LEVEL in the
oracle RMAN command
BACKUP INCREMENTAL LEVEL 0 database;

what does it mean the level ranges of 0,1,2,3


best regards


Sinan Kaygusuz
OCA

9. Incremental backups

A level N incremental backup backs up blocks that have changed since the
most recent incremental backup at level N or less.

9.1. Level 0 - the basis of the incremental backup strategy

RMAN> run {
2> allocate channel dev1 type disk;
3> backup
4> incremental level 0
5> filesperset 4
6> format '/oracle/backups/sunday_level0_%t'
7> (database);
8> release channel dev1;
9> }

Line#
4: Level 0 backup - backups of level > 0 can be applied to this
5: Specifies maximum files in the backupset

A list of the database backupsets will show the above backup. The 'type'
column is marked 'Incremental'; the 'LV' column shows '0'.

9.2. Example backup strategy using incremental backups

A typical incremental backup cycle would be as follows:

- Sun night - level 0 backup performed
- Mon night - level 2 backup performed
- Tue night - level 2 backup performed
- Wed night - level 2 backup performed
- Thu night - level 1 backup performed
- Fri night - level 2 backup performed
- Sat night - level 2 backup performed

If the database suffered a failure on Sat morning and this resulted in
a restore operation, RMAN could recover to the point of failure by
restoring the backups from Sunday, Thursday, and Friday. This is
because Thursdays level 1 backup contains all changes since Sunday, and
Friday's level 2 backup contains all changes since Thursday. Whether
the database could be completely recovered would depend on whether
archive logging is enabled.


10. Cumulative incremental backups

A cumulative incremental backup backs up all blocks that have changed since
the the most recent incremental backup at level N-1 or less (contrast with
non-cumulative incremental backups that backup blocks that have changed
since the the most recent incremental backup at level N or less). This
means that more work is done in performing the backup (duplication of
backup effort), but time may be saved when restoring (potentially fewer
backupsets to restore).