RMAN was introduced in Oracle 8i. Before Oracle 8i, we used traditional backup or scripted backup. Why did oracle move to RMAN backup? Why do we need to use RMAN to backup our database? We may already be doing online backup with some wonderfully crafted, home-grown scripts. We may ask this question ourselves. Why should we start using RMAN when my scripted backups are working fine?
We are moving to RMAN backup for two reasons. One is, when backup scripts breaks, the database backup would fail. Another issue is, when script fails, some one has to fix the backup scripts.
There are number of other positive reason to move to RMAN backup. Here are these….
- RMAN will detect corrupted blocks and report them to us. RMAN also can recover only corrupted blocks. This is called Block Media Recovery (BMR). In traditional recovery, we need to restore and recover the whole data file. But in RMAN, it is not required to restore and recover the entire data file for just few corrupted blocks.
- RMAN can back up your database online without having to put the tablespace in hot backup mode. Thus, the additional redo generated during a hot backup is reduced.
- RMAN will automatically track new datafiles and tablespaces for us. In scripted backup, we might need to change the backup script when new tablespace or data file is added in the database.
- RMAN will only backup up used data blocks (up to the high water mark(HWM)). So RMAN backup images typically are smaller than those of traditional online back images.
- RMAN provides easy, automated backup, restore and recovery operations. RMAN tracks all the backups needed to recover the database.
- RMAN can work fairly seamlessly with third-party media management products.
- RMAN supports incremental backup strategies.
- With RMAN, we can actually test backups without restoring them. We can validate the backup and make sure backup will work at the time of restore.
- If we use the repository, then RMAN provides a nice, centralized reporting facility.
- RMAN supports multiple archive log directories. If a failure occurs while backing up archived redo logs, Oracle will use one of the alternative archive log directories-if they are defined.
- Additionally, Oracle offers a graphical interface in Oracle Enterprise Manager (OEM). Also, an application programming interface (API) allows programmers to interface with RMAN and create programs that can manage backup and recovery.