Advantage/Difference of Image Copy over Backup Set

•RMAN supports binary compression of backup sets, where the backup set contents are compressed before being written to disk using a compression algorithm tuned for compression of datafiles and archived log files. But with Image copy no compression is done.

•A backup set never contains empty blocks. As RMAN passes through the datafiles, it simply skips blocks that have never been used. But image copy contains empty blocks. This means that backups of datafiles as backup sets are generally smaller than image copy backups and take less time to write. 

•Incremental backups can't be performed with Image copy but incremental backups can be taken over backup sets.

•RMAN can take backup of backup sets directly to tape, if you have installed the RMAN drivers for your tape library.But RMAN can't take backup of image copies directly to tape.

•Both Image copy and backup sets can be restored from RMAN. From Operating System Backup sets can't be generated or restored. 

•RMAN will check the contents for corruption for both Image copy and backupsets but native operating-system file copy utilities cannot check corruption while taking backup of Image copy.