1.1. Exploring the Features and Components of RMAN

RMAN has many capabilities to facilitate the backup and recovery process. RMAN comes in both web-based GUI and command-line versions. In general, RMAN performs and standardizes the backup and recovery process, which can reduce mistakes made during this process. Below is a list of some of the existing RMAN features:

• Backup databases, tablespaces, datafiles, control files, and archive logs

• Compressing backups by determining which blocks have changed, and backing up only those blocks

• Performing change-aware incremental backups

• Providing scripting capabilities to combine tasks

• Logging backup operations

• Integrating with third-party tape media software

• Providing reports and lists of catalog information

• Storing information about backups in a catalog in an Oracle database

• Offering performance benefits, such as parallel processing of backups and restores

• Creating duplicate databases for testing and development purposes

• Testing whether backups can be restored successfully

• Determining whether backups are still available in media libraries

RMAN has many improvements to support new functionality and different database failures that were not supported before Oracle 10g. In addition, RMAN can handle larger database backups and recoveries in quicker timeframes. This means less availability impact during the backup and recovery process. Here is a list of new 10g RMAN features:

• Migrating datafiles across operating system platforms

• User error recovery with flashback

• Automated tablespace point-in-time recovery (TSPITR)

• Dropping a database

• Using backup copies and flash recovery

• Creating and using RMAN backup copies

• Configuring default disk backup types

• Recovering datafiles not backed up

• Blocking change tracking

• Unregistering a database from the catalog

• Actual compression of RMAN backups

• Error-reporting improvements

RMAN has a rich feature set that is improving dramatically with each release of Oracle. These features allow you to back up and recover a database in almost any situation. Many of these new features address problems or difficulties that you will encounter in your daily tasks.

Other features such as flash recovery, block change tracking, and actual backup compression are innovations within RMAN that allow a DBA to support evolving database requirements.

The main components of RMAN are GUI or command-line access, the optional recovery catalog, the RMAN commands and scripting, and tape media connectivity. These components enable you to automate and standardize the backup and recovery process. Each component is described as follows:

GUI or command-line interface method

The web-enabled GUI or command-line interface (CLI) provides access to Recovery Manager. This process spawns off-server sessions that connect to the target database, which is the database that will be backed up. The GUI access is provided through the Oracle Enterprise Manager's web-based console. The Oracle Enterprise Manager (EM) tool performs backups, exports/imports, data loads, performance monitoring/tuning, job and event scheduling, and standard DBA management, to mention a few. The EM tool is a web-based application and must be run through a browser.

Recovery catalog

The recovery catalog is recovery information that is stored inside an Oracle database. This is similar to the RMAN repository stored in the control file, but information stored in the recovery catalog is more extensive. It is a special data dictionary of backup information that is stored in a set of tables, much like the data dictionary stores information about databases. The recovery catalog provides a method for storing information about backups, restores, and recoveries. This information can provide status on the success or failure of backups, operating system backups, datafile copies, tablespace copies, control file copies, archive log copies, full database backups, and the physical structures of a database.

RMAN commands

RMAN commands enable different actions to be performed to facilitate the backup and restore of the database. These commands can be organized logically into scripts, which can then be stored in the recovery catalog database. The scripts can be reused for other backups, thus keeping consistency among different target database backups.

Tape media connectivity

Tape media connectivity provides a method for interfacing with various third-party tape hardware vendors to store and track backups in automated tape libraries (ATLs). Oracle supports many tape hardware devices. ATLs are tape units that use robotics arms and bar-coded tapes to automate the usage of multiple tapes for backup purposes.