Configuring RMAN - Oracle RMAN for Absolute Beginners - page 102

Default Location
If you don't configure any RMAN variables and don't set up an FRA, by default RMAN allocates one disk-based
channel and writes the backup files to a default location. For example, you can run the following command without
configuring any RMAN parameters:

RMAN> backup database;

The default location varies by OS. In many Linux/Unix environments the default location is ORACLE_HOME/dbs .
The default format of the name of the backup files created is an OMF format; for example,

<ORACLE_HOME>/dbs/01ln9g7e_1_1

■ the default location is okay for small development databases. however, for most other environments (especially
production), you'll need to plan ahead for how much disk space you'll need for backups and explicitly set the location
for the backups via one of the other methods (such as implementing an fra or CONFIGURE CHANNEL ).

Tip

FRA
When backing up to disk, if you don't explicitly instruct RMAN to write the backups to a specific location (via the
FORMAT or CONFIGURE command), and you're using an FRA, RMAN automatically writes the backup files to directories
in the FRA. The files are stored in a subdirectory with the same name as the database's unique name. Also, the default
format of the name of the backup files created in the FRA is an OMF format; for example,

/<fra>/<dbuname>/backupset/<YYYY_MM_DD>/o1_mf_nnndf_TAG20100907T025402_68czfbdf_.bkp

I don't usually use an FRA for the placement of RMAN backups. In many of the environments I work in, there
isn't enough disk space on a single mount point to accommodate the entirety of the database backups. In such
situations, you need to allocate two or more channels that point to different mount points. Using an FRA in these
environments is somewhat unwieldy.
Also, for performance reasons, you may want to instruct RMAN to write to multiple disk locations. If you can
ensure that different mount points are based on different physical disks and are written to by separate controllers, you
can reduce I/O contention by allocating multiple channels pointing to separate mount points.
When you're using an FRA, RMAN automatically creates separate directories when backing up a database for the
first time on a given date. I prefer to have the backups written to one directory and not separate the directories and
backups by date. I find it easier to manage, maintain, and troubleshoot the backups if I use one standard directory for
each database on each server.

BACKUP...FORMAT
If you've configured an FRA and don't want to place RMAN backup files in the FRA automatically, you can directly
specify where you want backups to be placed when you issue the BACKUP command; for example,

RMAN> backup database format '/u01/O12C/rman/rman_%U.bkp';