Overview of the RMAN Environment

Overview of the RMAN Environment
July 14, 2009
Oracle Database RMAN
1. The Target Database
The target database is the database that you are backing up, restoring, or
recovering with RMAN.
2.he RMAN Client
RMAN is a command-line-oriented database client, much like SQL*Plus, with its
own command syntax. From the RMAN client you can issue RMAN commands
and SQL statements to perform and report on backup and recovery operations.
RMAN can take interactive input or read input from plain text files (called
command files). RMAN then communicates with one or more server processes
on the target database server which actually perform the work. You can also
access RMAN through the Enterprise Manager; for details see Oracle Enterprise
Manager Administrator's Guide.
The RMAN executable is typically installed in the same directory as the other
database executables. On Unix systems, for example, the RMAN executable is
located in $ORACLE_HOME/bin.
3. The RMAN Repository
RMAN maintains metadata about the target database and its backup and
recovery operations in the RMAN repository. Among other things, RMAN
stores information about its own configuration settings, the target database
schema, archived redo logs, and all backup files on disk or tape. RMAN's LIST,
REPORT, and SHOW commands display RMAN repository information.
The primary store for RMAN repository data is always the control file of the
target database. The CONTROL_FILE_RECORD_KEEP_TIME initialization
parameter controls how long backup records are kept in the control file before
those records are re-used to hold information about more recent backups.
Another copy of the RMAN repository data can also be saved in the recovery
catalog.
4. The Recovery Catalog
Using a recovery catalog preserves RMAN repository information if the control
file is lost, making it much easier to restore and recover following the loss of the
control file. (A backup control file may not contain complete information about
recent available backups.) The recovery catalog can also store a much more
extensive history of your backups than the control file, due to limits on the
number of control file records.
In addition to RMAN repository records, the recovery catalog can also hold
RMAN stored scripts, sequences of RMAN commands for common backup
tasks. Centralized storage of scripts in the recovery catalog can be more
convenient than working with command files.
Except for stored scripts, all of RMAN's features work equally well with or
without a recovery catalog. For more information on the recovery catalog see
Oracle Database Backup and Recovery Advanced User's Guide.
5. The Flash Recovery Area
The Automatic Disk-Based Backup and Recovery feature simplifies managing
disk space and files related to backup and recovery, by managing all backup and
recovery related files in a flash recovery area. You set the flash recovery area
location and size on disk, using the DB_RECOVERY_FILE_DEST and DB_
RECOVERY_FILE_DEST_SIZE initialization parameters. You also specify a
retention policy that dictates when backups may be discarded. RMAN then
manages your backup storage, deleting obsolete backups and backups already
copied to tape when space is needed, but keeping as many backups on disk as
space permits. This minimizes restores from tape during data recovery
operations to shorten restore and recovery times.
6. Media Managers
To access sequential media devices like tape libraries, RMAN uses third-party
media management software. A media manager controls these devices during
backup and recovery, managing the loading, labeling and unloading of media,
among other functions. Media management devices are sometimes called SBT
(system backup to tape) devices.
The Oracle Backup Solutions Program (BSP) works with vendors to help them
produce media management software for their devices. For enterprises that
already use media management software in their environment, many of those
software products can be directly integrated with RMAN. Contact your media
management software vendor for details about whether they participate in the
BSP and have an RMAN-compatible media management layer.