OCP 1Z0 052 79

79. You are working on a database that must be functioning 24 hours a day, 7 days a week. The database 
is configured in ARCHIVELOG mode.  
Which two options do you have for performing user-managed backups? (Choose two.) 
A.You can perform consistent backups only. 
B.You can perform a complete database backup without shutting down the database instance. 
C.You can back up data files only when all data files have the same SCN recorded in the control file. 
D.You can back up only those data files whose headers are frozen by using
ALTER TABLESPACE BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP commands. 


Answer: BD

A 非归档模式下才是只有冷备（也是一致性备份）

C 说法不正确，实例停止后，才会有scn一致的情况

SQL> SELECT file#, last_change# FROM v$datafile;     FILE# LAST_CHANGE#---------- ------------         1          2          3          4          5          6 6 rows selected