Oracle recommends a daily incremental backup strategy. In this backup strategy;
Day 1: Full backup is taken.
Day 2: Incremental backup is taken. (Incremental Level 0 Backup)
Day 3: Incremantal backup is taken. (Incremental Level 1 Backup)
The incremental backup taken the previous day is combined with the full backup (Level 0 ). This backup is called Incremental Cumulative backup.
In this backup strategy, the following path is followed in disaster situations.
When you want to go back to a time before Incremental Backup is taken after a Full backup is taken, Full backup is returned and archive redo logs are run on it.
After taking the Incremental backup on the 2nd day, if it is desired to return to a time before the Incremental backup on the 3rd day, the incremental level 0 backup on the 2nd day is returned and the archive redo logs are run on it.
When it is desired to return to a time before Incremental backup is taken on the 3rd day and before the 4th day Incremental backup is taken, archive redo log’ on top of the cumulative backup formed as a result of combining the level 0 incremental backup on the 2nd day with the level 1 incremental backup taken on the 3rd day. are operated.
The RMAN Script that makes this backup strategy is as follows.
RESYNC CATALOG FROM DB_UNIQUE_NAME ALL;
RECOVER COPY OF DATABASE WITH TAG 'dgbkup';
BACKUP DEVICE TYPE DISK INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG 'dgbkup' DATABASE;
BACKUP DEVICE TYPE SBT ARCHIVELOG ALL;
BACKUP BACKUPSET ALL;
DELETE ARCHIVELOG ALL;
RESYNC CATALOG FROM DB_UNIQUE_NAME ALL; Before starting to take backup, it connects to all databases and RESYNC the catalog.
RECOVER COPY OF DATABASE WITH TAG ‘dgbkup’; It processes the Level 1 Incremental Backup taken the previous day over the Level 0 backup. So we have Cumulative backup.
Day 1: Since we only have Level 0 backup, there will be no merge.
Day 2: There is a level 0 and level 0 incremental backup in my hand. Again, there is no merging.
Days 3 and Following: In addition to the backups we have, there is also Level 1 incremental backup. This backup is combined with the Level 0 incremental taken the previous day.
BACKUP DEVICE TYPE DISK INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG ‘dgbkup’ DATABASE; Creates Level 1 Incremental Backup.
Day 1: Level 0 backup is taken.
2nd and Subsequent Days: Level 1 incremental backup is taken.
BACKUP DEVICE TYPE SBT ARCHIVELOG ALL; Takes backup of archive logs to tape.
BACKUP BACKUPSET ALL; Takes backup of backup sets.
DELETE ARCHIVELOG ALL; Archive logs are deleted according to the setup specified in CONFIGURE ARCHIVELOG DELETION POLICY.