Incremental backups are useful for saving storage space because they backup only data blocks that have changed.
Rman compares the current files to a “base backup” (also called a “level 0 backup”)
Example , If you have a base backup and after changed something from the DB , you can run the following command for the changing blocks ;
RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE;If you don’t have any LEVEL 0 backup before this command , you will see ;
“no parent backup or copy of datafile 1 found”RMAN automatically creates a LEVEL 0 backup for its base incremental backup.