Level 1 backup created when no level 0 exists

(Doc ID 1392817.1)

Last updated on OCTOBER 12, 2016

Applies to:

Oracle Server - Enterprise Edition - Version: and later   [Release: 10.2 and later ]
Information in this document applies to any platform.


Since 10.2 it is possible to execute a level 1 incremental backup and for RMAN to produce a level 1 backup even though a level 0 backup doesn't exist.  The reason for this is because RMAN will copy all blocks changed since the file was created, see the following extract from the documentation for further clarification:

If no level 0 backup is available, then the behavior depends upon the compatibility mode setting. If compatibility is >=10.0.0, RMAN copies all blocks changed since the file was created, and stores the results as a level 1 backup. In other words, the SCN at the time the incremental backup is taken is the file creation SCN. If compatibility <10.0.0, RMAN generates a level 0 backup of the file contents at the time of the backup, to be consistent with the behavior in previous releases.

It's possible to execute the following query to check whether the level 1 backup has been created using the above method:
SQL> select file#, creation_change#, incremental_change#, checkpoint_change# from
v$backup_datafile where file# >0;


However, in 10g if you delete the level 0 backup, but retain any level 1 backups, RMAN will only check to see whether a previous level 1 backup exists and doesn't check for any level 0 backups, so allows a normal level 1 backup to be created.


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