Oracle Recovery Manager (RMAN) is a built-in tool provided with Oracle database that enables you to easily backup and recover the data in an automated manner, using either command-line mode or the Recovery Manager from within the Oracle Enterprise Manager. RMAN is designed to work intimately with the server, providing block-level corruption detection during backup and restore. RMAN optimizes performance and space consumption during backup with file multiplexing and backup set compression, and integrates with Oracle Secure Backup and third party media management products for tape backup.

The history of RMAN can be traced from the time the Traditional recovery (1990-1995) was introduced.  This recovery method requires restoration of failed database files and a roll-forward using Oracle’s Enterprise Backup Utility (EBU) or some termed it as "Oracle Recovery Manager Utility". Its disadvantage was that it took several hours to backup.  The Unix porting group for Oracle7 developed Enterprise Backup Utility (EBU), and considering it was using new/raw devices, it made backing up databases easier. Although EBU was a completely different tool and didn't work well; however, its concept gave birth to the current RMAN, i.e. it defined the Oracle Secure Backup (SBT) interface used by RMAN today. Nonetheless, RMAN has its own language to interact with and scripts can be written for common operations. Then RMAN parses and executes the language. RMAN generates PL/SQL blocks using templates defined in recover.bsq and execute the blocks using non-blocking Oracle Call Interface (OCI) calls (Cooksey & Nanda).

Now with over several years in the field, RMAN has undergone tremendous evolution and revolution, and it's gaining wide audiences, which is apparent by its wide adoption across the global Oracle customer base. Why? Because it uses database server to backup database, simplifies backup and restore operations using information in the recovery catalog, maintains database integrity by detecting block corruption during backups, eliminates performance overhead during backups, has built in reporting capabilities, maintains history of old backups and status of running backups, decreases time for specific types of recoveries by allowing block and tablespace point in time options, and it's free(Kuhn, & Schulze).

Over the past several years, Oracle has worked diligently to alleviate the problems in the older versions of RMAN associated with limited scripting capability, lack of scheduling support, standard edition limitations, no incremental backup support; does not auto resync in all cases, could not identify missing backup pieces during recovery, and could not to determine if a database is recoverable.

Now the newer RMAN keeps track of backups metadata in the control file or if a recovery catalog is being used, it will additionally store the metadata there. This is done by full resync, which is used to ensure that information about database physical structure is up-to-date. Further, the RMAN allows you to perform incremental and a cumulative physical backup of datafiles located in the flash recovery area greatly improves the performance of backups. The in-built block change-tacking file saves backup time. In addition, RMAN has the ability to span restlogs operations during recoveries, which means you can use all archived redo log files before and after an alter database resetlog operation to perform recovery (Freeman, 2008).

RMAN can now compress backup files as they are written, significantly lowering disk space requirement. RMAN also dynamically allocates the specified number of channels across all active RAC nodes, to perform the backup or restore operation. As a security measure, RMAN uses the Backup Set Encryption and catalog security for granting limited recovery catalog views to other users. The new RMAN has advanced tremendously that when I was reading this textbook “Oracle Database 11g, New Features” by Robert G. Freeman, I could decide which inform to summarize for this assignment. I’m quite sure there are some areas that need improvement but all the same it has matured considerably.


Reference:

Kuhn, D., Alapati, S., & Nanda, A. (2007). RMAN Recipes for Oracle Database 11g A Problem Solution Approach. Apress.

Rajan, C. (2007). Database Administrator II: Backup/Recovery & Network Administration. Thompson.

Powell, G. & McCollough-Dieter, C. (2007). Database Administrator: Implementation & Administration. Thompson.

Freeman, Robert G. (200). Oracle Database 11g, New Features. McGraw Hill-Orsbone

Kuhn, Darl, & Schulze, Scott: Oracle RMAN Pocket Reference
http://www.oreilly.com/catalog/rman/cover.html


Gorman, Tim. IS RMAN REALLY WORTH THE TROUBLE?
http://www.evdbt.com/TD_Rman.pdf

Oracle Database Backup and Recovery Advanced User's Guide 10g
http://www.stanford.edu/dept/itss/docs/oracle/10g/server.101/b10734/rcmconc1.htm

Cooksey, Donna and Nanda, Arup ORACLE RECOVERY MANAGER 10g: Exploring RMAN’s Unique Data Recovery Capabilities
http://www.oracle.com/technology/deploy/availability/pdf/1181_Cooksey_WP.pdf