QUESTION 143
Which statement about recovering from the loss of aredo log group is true?
A. If the lost redo log group is ACTIVE, you should first attempt to clear the log file.
B. If the lost redo log group is CURRENT, you must clear the log file.
C. If the lost redo log group is ACTIVE, you must restore, perform cancel-based incomplete recovery, and
open the database using the RESETLOGS option.
D. If the lost redo log group is CURRENT, you must restore, perform cancel-based incomplete recovery, and
open the database using the RESETLOGS option.
Answer: D
同49题：http://blog.csdn.net/rlhua/article/details/14093273
Explanation/Reference:
Section: Backup, Recovery & Recovery Manager (RMAN)
If the lost redo log group is CURRENT, you must restore, perform cancel-based incomplete recovery, and open
the database using the RESETLOGS option. A redo log group with a CURRENT status indicates that LGWR is
currently writing to it. To recover from this failure, you must restore the database from a whole backup and
perform cancel-based incomplete recovery. Then, you should open the database using the RESETLOGS
option.
The option that states if the lost redo log group is ACTIVE, you should first attempt to clear the log file is
incorrect. If the lost redo log group has a status of ACTIVE, it is needed for instance recovery. In that situation,
you should first attempt to perform a checkpoint. After the checkpoint, the log file is no longer required for
instance recovery.
The option that states if the lost redo log group is CURRENT, you must clear the log file is incorrect.You would
clear the log file only if the status of the lost redo log group was INACTIVE. After clearing the log file, the log
file may be reused.
The option that states if the lost redo log group is ACTIVE, you must restore, perform cancel-based incomplete
recovery, and open the database using the RESETLOGS option. These actions are only necessary if the log
file has a CURRENT status, which indicates LGWR is currently writing to it.