You issue the following command:
RMAN>CONFIGURE BACKUP OPTIMIZATION ON;
What is the result of this command on your backups?
A. An incremental backup strategy will be used automatically.
B. Read-only datafiles will not be backed up as long as backups of those files already exist and those
backups meet established retention criteria.
C. RMAN will configure itself for maximum performance at the cost of CPU.
D. RMAN will configure itself for minimal OS/CPU impact at the cost of time to back up the database.
E. RMAN will automatically compress backups.
Backup optimization is a feature whereby Oracle will not back up a read-only tablespace as long as that tablespace has been backed up such that it meets the backup retention criteria.
原文：http://www.cnblogs.com/Babylon/p/7810795.html