You want to take a complete database backup using RMAN. The backup should consist only the used blocks from your database.
Which two statements are true about this backup operation? (Choose two.)
A.
Backup compression should be enabled
B.
Parallelism for the channel should be set to 2
C.
All the files must be backed up as backup sets
D.
The backup may be stored either on disk or on media with media manager
I don’t know why these are answer? please explain it
Many thanks!
The backup should consist only the used blocks from your database.so,it must be backupset. and backupset can be stored on disk or tape.
Thanks so much!
But how about A answer? : Backup compression should be enabled
To answer Omni, the “AS COMPRESSED BACKUPSET” option of the RMAN BACKUP command allows RMAN to perform binary compression and they are automatically decompressed during recovery. It doesn’t check if the blocks are used or not
that’s related with the comparison of back up sets&image copies. In a reverse logical manner, you can not use image copies for such type of backup ( backups of only used blocks ), and image copies may be stored only on disks.
I think A is about binary compression of the backup set not about unused block compression.
To answer Omni, the “AS COMPRESSED BACKUPSET” option of the RMAN BACKUP command allows RMAN to perform binary compression and they are automatically decompressed during recovery. It doesn’t check if the blocks are used or not