Oracle OCP 1Z0 053 Q517(Block Media Recovery&Archivelog Mode&Flashback Logging)

517.Which of the following are true concerning block media recovery? (Choose all that apply.)
A. Any gap in archive logs ends the recovery.
B. If a gap in archive logs is encountered, RMAN will search forward for newer versions of the blocks that are not corrupt.
C. Uncorrupted blocks from the flashback logs may be used to speed recovery.
D. The database can be in NOARCHIVELOG mode.
E. None of the above.
Answer: BC

1. 資料庫必須是歸檔模式或者使用的當前的控制檔案掛載, D錯誤

官方文件：http://docs.oracle.com/cd/B28359_01/backup.111/b28270/rcmblock.htm#CHDFHEID

Prerequisites for Block Media Recovery

The following prerequisites apply to the RECOVER ... BLOCK command:

• The target database must run in ARCHIVELOG mode and be open or mounted with a current control file.

• If the target database is a standby database, then it must be in a consistent state, recovery cannot be in session, and the backup must be older than the corrupted file.

• The backups of the datafiles containing the corrupt blocks must be full or level 0 backups and not proxy copies.

  If only proxy copy backups exist, then you can restore them to a nondefault location on disk, in which case RMAN considers them datafile copies and searches them for blocks during block media recovery.

• RMAN can use only archived redo logs for the recovery.

  RMAN cannot use level 1 incremental backups. Block media recovery cannot survive a missing or inaccessible archived redo log, although it can sometimes survive missing redo records.

• Flashback Database must be enabled on the target database for RMAN to search the flashback logs for good copies of corrupt blocks.

  If flashback logging is enabled and contains older, uncorrupted versions of the corrupt blocks, then RMAN can use these blocks, possibly speeding up the recovery.

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