Introduction to RMAN

Introduction to Recovery Manager

Recovery Manager (RMAN) is an Oracle utility that can back up, restore, and recover database files. The product is a feature of the Oracle database server and does not require separate installation.

Recovery Manager is a client/server application that uses database server sessions to perform backup and recovery. It stores metadata about its operations in the control file of the target database and, optionally, in a recovery catalog schema in an Oracle database.

You can invoke RMAN as a command-line executable from the operating system prompt or use some RMAN features through the Enterprise Manager GUI.

Why Use RMAN?

Most production database systems impose stringent requirements on backup and recovery. As a DBA in charge of backup and recovery, you must:

• Manage the complexity of backup and recovery operations
• Minimize the possibility of human error
• Make backups scalable and reliable
• Utilize all available media hardware
• Make backups proportional to the size of transactional changes, not to the size of database
• Make recovery time proportional to the amount of data recovered

You have two basic methods for performing these backup and recovery tasks on an Oracle release 8.0 or higher database:

• Using operating system commands to perform backup and restore operations, and SQL or SQL*Plus statements to perform recovery
• Using Recovery Manager for backup, restore, and recovery
  

Overview of the RMAN Environment

The RMAN environment consists of the utilities and databases that play a role in a backup and recovery strategy. A typical RMAN setup utilizes the following:

• RMAN executable
• Target database
• Recovery catalog database
• Media management software

Of these components, only the RMAN executable and target database are required. RMAN automatically stores its metadata in the target database control file, so the recovery catalog database is optional. Nevertheless, maintaining a recovery catalog is strongly encouraged. If you create a catalog on a separate machine, and if the production machine fails completely, then you have all the restore and recovery information you need in the catalog.

This section contains these topics:

• About the RMAN Executable
• About the Target Database
• About the RMAN Repository
• About the RMAN Media Management Interface

About the RMAN Executable

The RMAN executable is automatically included with the Oracle software installation. Its location is platform-specific and is typically located in the same place as the other Oracle executables. On Unix systems, for example, the RMAN executable is located in $ORACLE_HOME/bin.

To start the executable, simply enter the filename on the command line. For example, on a UNIX system, enter:

% rman

About the Target Database

The target database is the database that RMAN is backing up, restoring, or recovering. You can use a single recovery catalog in conjunction with multiple target databases. For example, assume that your data center contains 10 databases of varying sizes. You can use a single recovery catalog located in a different data center to manage the metadata from all of these databases.

About the RMAN Repository

The RMAN repository is a set of metadata that RMAN uses to store information about the target database and its backup and recovery operations. Among other things, RMAN stores information about:

• Backup sets and pieces
• Image copies (including archived redo logs)
• Proxy copies
• The target database schema
• Persistent configuration settings

You can access this metadata by issuing LIST, REPORT, and SHOW commands in the RMAN interface, or by using SELECT statements on the catalog views (only if you use a recovery catalog).