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.
一致性备份必须在数据库正常关闭的情况下进行，这个时候 redo，数据文件和控制文件的 scn 都是一致的
原文：http://www.cnblogs.com/Babylon/p/8004946.html