Database Reference
In-Depth Information
If the status is
INACTIVE
and the log has been archived, you can use the
clear logfile
command to re-create the
log group, as shown here:
SQL> alter database clear logfile group <group#>;
If the status is inactive and the log group has not been archived, then re-create it with the
clear unarchived
logfile
command, as shown here:
SQL> alter database clear unarchived logfile group <group#>;
If the cleared log group had not been previously archived, it's critical that you immediately create a backup of
your database. See Chapter 5 for details on creating a complete backup of your database.
An online redo log group with an
ACTIVE
status is still required for crash recovery. If all members of an active
online redo log group experience media failure, then you must attempt to issue a checkpoint. If the checkpoint is
successful, then you can clear the log group. If the checkpoint is unsuccessful, then you will have to perform an
incomplete recovery.
If the checkpoint is successful and if the log group has not been archived, then the log may be required for media
recovery. Back up your database as soon as possible in this situation. The unarchived log group may be needed for
media recovery if the last database backups were taken before the redo information in the log was created. This means
if you attempt to perform media recovery, you won't be able to recover any information in the damaged log file or any
transactions that were created after that log.
Recovering After Loss of All Members of Current Redo Log Group
If all of the members of a current Online redo logs:recovery online redo log group in your database have experienced
media failure then (unfortunately) your alternatives are limited when you lose all members of a current online redo
log group. Here are some possible options:
•
Perform an incomplete recovery up to the last good SCN.
•
If flashback is enabled, flash your database back to the last good SCN.
•
If you're using Oracle Data Guard, fail over to your physical or logical standby database.
•
In preparation for an incomplete recovery, first determine the last good SCN by querying the
FIRST_CHANGE#
column from
V$LOG
. In this scenario, you're missing only the current online redo logs. Therefore, you can perform an
incomplete recovery up to, but not including, the
FIRST_CHANGE#
SCN of the current online redo log.
Contact Oracle Support for suggestions.
SQL> shutdown immediate;
SQL> startup mount;
Now issue this query:
SELECT group#, status, archived,
thread#, sequence#, first_change#
FROM v$log;
