Parallelization of BackupSets and Backup Options

Parallelization of Backup Sets
Parallelization of backup sets is performed by causing multiple backup sets to be concurrently backed up over multiple device channels. This is done by allocating multiple channels, one for each backup set that needs to be concurrently backed up before the backup process occurs. You can either modify the CONFIGURE settings for channel parallelism greater than 1 or use manual channel allocation.

RMAN> run
{
allocate channel c1 type disk;
allocate channel c2 type disk;
backup
(datafile 1, 2, 3 channel c1)
(archivelog all channel c2);
}

The automated method of parallelizing your backup requires modifying the CONFIGURE setting of parallelization parameter.
RMAN> configure device type disk parallelism 3;
RMAN> backup
(datafile 1, 2)
(datafile 3, 4)
(archivelog all);

Backup Options
RMAN provides many options for the backup process. These options control filenames, backup performance, and the size of backups. Options that control filenames are handled with FORMAT and TAG parameters with BACKUP command. The RATE option limits backup I/O bandwidth usage on a computer. This limits RMAN from consuming all of a server’s resources during backup operations. The DURATION option determines the maximum time a backup can process before being terminated. The options that control sizes are MAXSETSIZE and MAXPIECESIZE. These options limit the size of backup sets and backup pieces.

RMAN> backup tablespace users format=’user_bs_%d%p%s’;

RMAN> backup as copy tablespace users format=’C:\oracle\backup\ora101c\users_%d%p%s’;

RMAN> backup database tag weekly_backup;

The RATE option is designed to limit RMAN from using excessive system resources during backup and restore operations.
RMAN> configure channel device type disk rate 5M;

RMAN> configure channel device type disk maxsetsize=10G;
RMAN> backup database maxsetsize=10G;

RMAN> configure channel device type disk maxpeicesize=2G;

NOTE: Caution must be taken when using MAXSETSIZE parameter. If the datafile being backed up is larger than the MAXSETSIZE parameter, the backup will fail.