A、A database backup, combined with archived redo log files, guarantees that all committed data can be recovered to the point of failure. 

B、During recovery the ARCn background process copies its redo entries identified for recovery by the control file to the data files. 

C、After each write to an archived log, the mandatory background process ARCn writes its log sequence number and the first and last SCN number within the log sequence to the control file. 

D、At database recover time, and archived redo log is uniquely identified for recovery use by its redo thread number and destination ID number retrieved from the control file.