RMAN vs OS backup on NetAppBefore RMAN emerged, OS backup is the main way to backup a database. It has shortcomings:
- Cannot do incremental backup. If datafiles are big, the backup time is long
- It takes more disk space
- You cannot really know whether your backup will come to rescue in disaster. RMNA offer the ability to validate the backup
RMAN offers the following bonous beyond the normal backup
- RMAN can compress the backup
- RMAN can check the corrupted data block during backup.
- RMAN can delete obsolete backup set
One shortcoming of RMAN is that you have to maintain a repository server to make full use of RMAN.
The pendulum has swayed so far in favour to RMAN that OS backup seems to be dead.
NetApp’s Snapshot change the balance a bit, if not completed reverse the trend.With Snapshot,
the backup time is long. The backup process almost take no tiime and the size of DB is irrelevant. I now take backup every hour. It takes more disk spaceSnapshot do incremental backup at OS level. RMAN can compress backupWith OS level incremental backup, this is not important
- MAN can check the corrupted data block during backup Still an advantage
_RMAN can delete obsolete backup setSnapshots can be deleted by a scripts
- The backup is superfast
- Restore is easy. Just normal OS copy. It should be a little faster than RMAN restore since RMAN need to restore the backupsets to OS files.
- Get rid of repository server.
I have not got a chance to test “SnapManager for Oracle”, which combine Snapshot with RMAN. Maybe after I do that, I will have different opinion.
So far, Snapshot + OS backup will supersede RMAN.