You want RMAN to make duplicate copies of data files when using the backup command. What must you set using the RMAN configure command to achieve this? 

Answer options:

A. MAXSETSIZE TO 2;
B. DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET;
C. CHANNEL DEVICE TYPE DISK FORMAT `/disk1/%U` , `/disk2/%U`;
D. DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2;

D

Reference: http://docs.oracle.com/cd/B14117_01/server.101/b10734/rcmconfg.htm http://docs.oracle.com/cd/B28359_01/backup.111/b28270/rcmconfa.htm#BRADV137