Question

How does one backup a database using RMAN? (for DBA

Answer 1

The biggest advantage of RMAN is that it only backup used space in
the database. Rman doesn't put tablespaces in backup mode, saving
on redo generation overhead. RMAN will re-read database blocks until
it gets a consistent image of it. Look at this simple backup example.
rman target sys/*** nocatalog
run {
allocate channel t1 type disk;
backup
format '/app/oracle/db_backup/%d_t%t_s%s_p%p'
( database );
release channel t1;
}
Example RMAN restore:
rman target sys/*** nocatalog
run {
allocate channel t1 type disk;
# set until time 'Aug 07 2000 :51';
restore tablespace users;
recover tablespace users;
release channel t1;
}
The examples above are extremely simplistic and only useful for
illustrating basic concepts. By default Oracle uses the database
controlfiles to store information about backups. Normally one would
rather setup a RMAN catalog database to store RMAN metadata in.
Read the Oracle Backup and Recovery Guide before implementing any
RMAN backups.
Note: RMAN cannot write image copies directly to tape. One needs to
use a third-party media manager that integrates with RMAN to backup
directly to tape. Alternatively one can backup to disk and then
manually copy the backups to tape.