At a minimum, the environment for RMAN requires:
·
The target database that is required to be backed up
·
The RMAN client
Other optional components are:
·
Media Management Software
·
Flash Recovery Area
·
Recovery Catalog Database
Target Database
It is the database which needs to be backed up, restored or
recovered using RMAN. The target database's control file is used by RMAN to
gather information about the target database and to store information about
RMAN's own operations.
RMAN Client
It is here where RMAN commands and SQL statements can be
issued for performing backup and restoring operations. RMAN client uses Oracle
Net to connect to the target database. So locating a RMAN client to any host
that is connected to the target host through Oracle Net will do the job.
The above two are the required components for performing
backup or restoring using RMAN. The components described below are the optional
components.
Media Management Software
Media management software is used by RMAN to handle
sequential media devices (for example: tape libraries, etc.).The media manager
controls these devices during backup and recovery operations. It manages the
loading, labeling, unloading of media, among all other functions performed by
it. Actually, what happens during backup or restore operation, RMAN client get
connected to target instance and it is this instance which is directed to
communicate with the media manger. So instead of having a direct communication
between RMAN client and media manager, the communication happens through the
target instance.
Flash Recovery Area
RMAN has a feature known as Automatic Disk-based Backup and
Recovery that manages all the related files of backup and recovery in a flash
recovery area. This feature thus simplifies managing disk space and files
related to backup and recovery operations. The flash recovery area parameter
can be set using:
·
db_recovery_file_dest – This parameter determines the location of
the flash recovery area.
·
db_recovery_file_dest_size – This parameter determines how much
space can be used by Oracle in the flash recovery area.
There can be a need to assign flash recovery area more
space, which typically depends on:
·
The size of the database
·
The number of backups one wants or requires to keep
·
If the database is being run in ARCHIVELOG mode
Recovery Catalog Database
The Recovery catalog can be used to hold RMAN repository
records, RMAN stored scripts, and the sequences of RMAN commands for common
backup tasks. Actually, it can be more convenient to work with the centralized
store of scripts than working with command files.