RMAN parallelization of backup set

RMAN> RUN {
 ALLOCATE CHANNEL C1 TYPE DISK;
 ALLOCATE CHANNEL C2 TYPE DISK;
 ALLOCATE CHANNEL C3 TYPE DISK;
 BACKUP
 INCREMENTAL LEVEL=0
 FORMAT 'C:\BACKUP1\%c_%d_%p.bak'
 (datafile 1,4,5 CHANNEL C1 TAG=DF1)
 (DATAFILE 2,3,9 CHANNEL C2 TAG=DF2)
 (DATAFILE 6,7,8 CHANNEL C3 TAG=DF3);
 SQL 'ALTER SYSTEM ARCHIVE LOG CURRENT';
 }