compress and Parallelizing Backups

RMAN> run
2> {
3> allocate channel d1 device type disk;
4> allocate channel d2 device type disk;
5> allocate channel d3 device type disk;
6> backup as compressed backupset database;
7> }

allocated channel: d1
channel d1: SID=130 device type=DISK

allocated channel: d2
channel d2: SID=132 device type=DISK

allocated channel: d3
channel d3: SID=134 device type=DISK

Starting backup at 04-APR-10
channel d1: starting compressed full datafile backup set
channel d1: specifying datafile(s) in backup set
input datafile file number=00002 name=D:\11GSOFTWARE\ORADATA\SANDEEP\SYSAUX01.DBF
channel d1: starting piece 1 at 04-APR-10
channel d2: starting compressed full datafile backup set
channel d2: specifying datafile(s) in backup set
input datafile file number=00001 name=D:\11GSOFTWARE\ORADATA\SANDEEP\SYSTEM01.DBF
input datafile file number=00004 name=D:\11GSOFTWARE\ORADATA\SANDEEP\USERS01.DBF
channel d2: starting piece 1 at 04-APR-10
channel d3: starting compressed full datafile backup set
channel d3: specifying datafile(s) in backup set
input datafile file number=00005 name=D:\11GSOFTWARE\ORADATA\SANDEEP\EXAMPLE01.DBF
input datafile file number=00003 name=D:\11GSOFTWARE\ORADATA\SANDEEP\UNDOTBS01.DBF
channel d3: starting piece 1 at 04-APR-10
channel d3: finished piece 1 at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\BACKUPSET\2010_04_04\O1_MF_NNNDF_TAG20100404T181724_5VKLFF9N_.BKP tag=TAG20100404T181724 comment=NONE
channel d3: backup set complete, elapsed time: 00:00:46
channel d1: finished piece 1 at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\BACKUPSET\2010_04_04\O1_MF_NNNDF_TAG20100404T181724_5VKLF7Y2_.BKP tag=TAG20100404T181724 comment=NONE
channel d1: backup set complete, elapsed time: 00:02:41
channel d2: finished piece 1 at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\BACKUPSET\2010_04_04\O1_MF_NNNDF_TAG20100404T181724_5VKLFBCQ_.BKP tag=TAG20100404T181724 comment=NONE
channel d2: backup set complete, elapsed time: 00:03:28
Finished backup at 04-APR-10

Starting Control File and SPFILE Autobackup at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\AUTOBACKUP\2010_04_04\O1_MF_S_715458057_5VKLMVLS_.BKP comment=NONE
Finished Control File and SPFILE Autobackup at 04-APR-10
released channel: d1
released channel: d2
released channel: d3

RMAN>