You have enabled backup optimization for the RMAN environment. Identify two criteria on which RMAN will skip the file, if it has already been backed up.() (Choose two.)
A:The data file backup is done with multiple channels
B:The data files is in the read-write mode after being backed up in the read only mode
C:The backup was taken after the data files was taken offline-normal or is in the read only mode
D:The data file backup complies with the back retention policy and the backup duplexing feature
出自:Oracle认证