Database Reference
In-Depth Information
Recovering After Loss of All Members of Active Redo Log Group
If all the members of an active online redo log group in your database have experienced media failure, then perform
the following steps when restoring an active online redo log group:
1.
Verify the damage to the members.
Verify that the status is
ACTIVE
.
2.
3.
Attempt to issue a checkpoint.
If the checkpoint is successful, the status should now be
INACTIVE
, and you can clear the
log group.
4.
5.
If the log group that was cleared was unarchived, back up your database immediately.
6.
If the checkpoint is unsuccessful, then you will have to perform incomplete recovery.
Inspect your target database
alert.log
file, and verify the damage. You should see a message in the alert.log file
identifying the bad members:
ORA-00312: online log 2 thread 1: '/u01/oraredo/O12C/redo02a.rdo'
ORA-00312: online log 2 thread 1: '/u02/oraredo/O12C/redo02b.rdo'
Next, verify that the damaged log group has an
ACTIVE
status as follows:
$ sqlplus / as sysdba
SQL> startup mount;
Run the following query:
SQL> select group#, status, archived, thread#, sequence# from v$log;
Here is some sample output:
GROUP# STATUS ARC THREAD# SEQUENCE#
------ ---------------- --- -------- ----------
1 CURRENT NO 1 92
2 ACTIVE YES 1 91
3 INACTIVE YES 1 90
If the status is ACTIVE, then attempt to issue an alter system checkpoint command, as shown here:
SQL> alter system checkpoint;
System altered.
If the checkpoint completes successfully, then the active log group should be marked as
INACTIVE
. A successful
checkpoint ensures that all modified database buffers have been written to disk, and at that point, only transactions
contained in the CURRENT online redo log will be required for crash recovery.
■
if the checkpoint is unsuccessful, you will have to perform incomplete recovery. see the section in this chapter
“Recovering After loss of All Members of Current Redo log group” for a full list of options in this scenario.
Note
