Oracle 11g Feature Multisection Backup.

With this new feature RMAN backups can be split 
into multiple pieces.

Suppose you want to backup your system tablespace and spread the 
backups to three different backup locations.
You can do so through the following query.

RMAN> run {
 allocate channel c1 type disk format '/dest1/%U';
 allocate channel c2 type disk format '/dest1/%U';
 allocate channel c3 type disk format '/dest1/%U';
 backup
 section size 200M
 tablespace system;
}     

In the above query the backups of the system tablespace will be done
to three different locations with backup chunks of 200M each.

After backup you can find your datafile number for the tablespace
system by using the following command:

RMAN> report schema;

Then the backups of a particular datafile can be checked
by using the following command:

RMAN> list backup of datafile 1;