569.Which are the correct steps, in order, to deal with the loss of an online redo log if the database has not yet crashed?
A. Issue a checkpoint.
B. Shut down the database.
C. Issue an alter database open command to open the database.
D. Startup mount the database.
E. Issue an alter database clear logfile command.
F. Recover all database datafiles.
G. a, b, c, d
H. b, d, e, c
I. a, b, d, e, c
J. b, f, d, f, c
K. b, d, a, c
Answer: C
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/backup.112/e10642/osadvsce.htm#BRADV90049
Recovering After Losing All Members of an Online Redo Log Group
If a media failure damages all members of an online redo log group, then different scenarios can occur depending on the type of online redo log group affected by the failure and the archiving mode of the database.
If the damaged online redo log group is current and active, then it is needed for crash recovery; otherwise, it is not. Table 30-4 outlines the various recovery scenarios.
Table 30-4 Recovering After the Loss of an Online Redo Log Group
| If the Group Is... | Then... | And You Should... |
|---|---|---|
|
Inactive |
It is not needed for crash recovery |
Clear the archived or unarchived group. |
|
Active |
It is needed for crash recovery |
Attempt to issue a checkpoint and clear the log; if impossible, then you must either use Flashback Database or restore a backup and perform incomplete recovery up to the most recent available redo log. |
|
Current |
It is the redo log that the database is currently writing to |
Attempt to clear the log; if impossible, then you must either use Flashback Database or restore a backup and perform incomplete recovery up to the most recent available redo log. |