OCP 1Z0 052 76

76.  Which  statement  is  true  about  a  whole  consistent  database  backup  on  a  database  running  in
ARCHIVELOG mode?  
A.The backup will consist of used data blocks only. 
B.The database must be shut down to accomplish the backup. 
C.The backup can be accomplished without shutting down the database. 
D.The backup will contain all database files that have never been backed up.  
Answer: B

当在open模式下时，数据是变动的，这时data file的scn为空，备份的数据不是一致的。

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

见文档是一致性备份的例子

http://docs.oracle.com/cd/E11882_01/backup.112/e10643/rcmsynta006.htm#RCMRF90004

Example 2-13 Making a Consistent Database Backup

Assume that the database is open and you want to make a consistent backup of the whole database. This example shuts down the database consistently, mounts the database, makes a consistent whole database backup, and then opens the database.

SHUTDOWN IMMEDIATE;STARTUP MOUNT;BACKUP DATABASE PLUS ARCHIVELOG;# Now that the backup is complete, open the database.ALTER DATABASE OPEN;

Example 2-14 Mounting the Database After Restoring the Control File

This example restores the control file, mounts it, and performs recovery. Finally, the example resets the online redo log.

STARTUP FORCE NOMOUNT;RESTORE CONTROLFILE FROM AUTOBACKUP;ALTER DATABASE MOUNT;# You must run the RECOVER command after restoring a control file even if no # datafiles require recovery.RECOVER DEVICE TYPE DISK DATABASE;ALTER DATABASE OPEN RESETLOGS;