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A complete high availability and disaster recovery strategy requires dependable data backup, restore, and recovery procedures. Oracle Recovery Manager (RMAN), a command-line and Enterprise Manager-based tool, is the Oracle-preferred method for efficiently backing up and recovering your Oracle database. 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.
RMAN takes care of all underlying database procedures before and after backup or restore, freeing dependency on OS and SQL*Plus scripts. It provides a common interface for backup tasks across different host operating systems, and offers features not available through user-managed methods, such as parallelization of backup/recovery data streams, backup files retention policy, and detailed history of all backups.
Overview of RMAN Functional Components
The RMAN environment consists of the utilities and databases that play a role in backing up your data. At a minimum, the environment for RMAN must include the following:
The target database to be backed up
The RMAN client, which interprets backup and recovery commands, directs server sessions to execute those commands, and records your backup and recovery activity in the target database control file.
Some environments will also use these optional components:
A flash recovery area, a disk location in which the database can store and manage files related to backup and recovery
Media management software, required for RMAN to interface with backup devices such as tape drives
A recovery catalog database, a separate database schema used to record RMAN activity against one or more target databases
New Features in Oracle Database 11g
Data Recovery Advisor
The Data Recovery Advisor is a new tool aimed at reducing a user’s time spent analyzing and formulating a suitable recovery plan for a given failure. A ‘failure’ in the context of the DRA can be a missing, inaccessible, or wrong version of a file (e.g. control file, data file), physical corruptions resulting from I/O errors, or logical block inconsistency. After identifying all current failures, the DRA then recommends the optimal, feasible recovery plan, and if the user desires, automatically executes a selected recovery plan. All DRA functions can be accessed via EM or RMAN’s command-line interface.
Multisection Backups
RMAN can back up or restore a single file in parallel by dividing the work among multiple channels. Each channel backs up one file section, which is a contiguous range of blocks. This speeds up overall backup and restores performance, and particularly for bigfile tablespaces, in which a data file can be sized upwards of several hundred GB to TB's.
Fast Backup Compression
In addition to the Oracle Database 10g backup compression algorithm (BZIP2), RMAN now supports the ZLIB algorithm, which offers 40% better performance, with a trade-off of < 20% lower compression ratio, versus BZIP2.
Network-enabled Database Duplication
A clone database on a remote site can now be easily created directly over the network with the enhanced DUPLICATE command, without the need for existing backups.
Virtual Private Catalog
A recovery catalog administrator can grant visibility of a subset of registered databases in the catalog to specific RMAN users.
Integration with Windows Volume Shadow Copy Services (VSS)
The Oracle database can participate in the VSS infrastructure on Windows platforms, with compatible backup management applications and storage systems. This feature allows VSS-enabled backup management applications to snapshot the Oracle database and restore at the datafile, tablespace, or database level.
For more details on Oracle Recovery Manager can view on ORACLE DBA SUPPORT
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