RMAN> run

{

allocate channel c1 type disk;

allocate channel c2 type disk;

backup

(datafile 1,2,3 channel c1)

(archivelog all channel c2);

 

RMAN> run

{

allocate channel c1 type disk;

allocate channel c2 type disk;

backup

(database channel c1)

(archivelog all channel c2);

 

RMAN> configure device type disk parallelism 3;

 

RMAN> backup

(datafile 1,2)

(datafile 3,4)

(archivelog all);