For any use of the BACKUP command creates backup sets, you can take advantage of RMAN support for binary compression of backup sets by using the as compressed backupset option to the BACKUP command. The resulting backup sets are compressed using an algorithm for the efficient compression of Oracle database optimized files. No additional steps are required uncompression in restoring, if you use RMAN integrated compression.
The primary disadvantage of using RMAN binary compression is performance overhead during backups and restores.Backup performance when creating compressed backup sets is CPU bound. If you have more than one CPU, you can run parallel jobs on multiple CPUs and thus improve the performance of increased use.
This example shows; backs up the entire database and archived logs to the configured default backup destination (disk or tape), producing compressed backupsets:
BACKUP AS COMPRESSED BACKUPSET DATABASE PLUS ARCHIVELOG;
This example shows ;backs up several datafiles to the default device, using binary compression:
BACKUP AS COMPRESSED BACKUPSET DATAFILE 1,2,4;