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Recovering After loss of all members of the CURRENT redo log group

 

All of the members of a current online redo log group in your database have experience media failure.

You lose all members of a current online redo log group. Here are possible reasons,

  • 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.

SQL> select group#,status,archived,thread#,sequence# from v$log;

GROUP# STATUS           ARC    THREAD#  SEQUENCE#
———- —————- — ———- ———-
1 CURRENT          NO           1         17
2 INACTIVE         YES          1         15
3 INACTIVE         YES          1         16

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  285212672 bytes
Fixed Size                  1218992 bytes
Variable Size              92276304 bytes
Database Buffers          188743680 bytes
Redo Buffers                2973696 bytes
Database mounted.
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo01.log’
ORA-00312: online log 1 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo01a.log’

SQL> select group#,status,archived,thread#,sequence# from v$log;

GROUP# STATUS           ARC    THREAD#  SEQUENCE#
———- —————- — ———- ———-
1 CURRENT          NO           1         17
3 INACTIVE         YES          1         16
2 INACTIVE         YES          1         15

SQL> alter system checkpoint;
alter system checkpoint
*
ERROR at line 1:
ORA-01109: database not open

First determine the last good SCN by querying the first_change# column from v$log, you’re missing only the current online redo logs, therfore you can perform an incomplete recovery up tobut not including,

SQL> select group#,status,archived,thread#,sequence#,first_change# from v$log;

GROUP# STATUS           ARC    THREAD#  SEQUENCE# FIRST_CHANGE#
———- —————- — ———- ———- ————-
1 CURRENT          NO           1         17        574131
3 INACTIVE         YES          1         16        574125
2 INACTIVE         YES          1         15        574103

SQL>

In this case, you can restore and recover up to but not including, 574131

Operation :-

Losing  all members of your current online redo log group is arguably the worst thing taht can happen to your database. if you experience media failure with all members of the current online redo group, then you will lose any transactions contained in those logs. in this case, you will have to perform incomplete recovery before you can open your database.

[oracle@localhost root]$ rlwrap rman target sys/azar

Recovery Manager: Release 10.2.0.1.0 – Production on Mon May 31 10:51:10 2010

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

connected to target database: TEST (DBID=2015564632, not open)

RMAN> restore database until scn 574131;

Starting restore at 31-MAY-10
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=150 devtype=DISK

channel ORA_DISK_1: starting datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
restoring datafile 00001 to /home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/system01.dbf
restoring datafile 00002 to /home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/undotbs01.dbf
restoring datafile 00003 to /home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/sysaux01.dbf
restoring datafile 00004 to /home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/users01.dbf
channel ORA_DISK_1: reading from backup piece /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/backupset/2010_05_25/o1_mf_nnndf_TAG20100525T103307_5zpz9nft_.bkp
channel ORA_DISK_1: restored backup piece 1
piece handle=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/backupset/2010_05_25/o1_mf_nnndf_TAG20100525T103307_5zpz9nft_.bkp tag=TAG20100525T103307
channel ORA_DISK_1: restore complete, elapsed time: 00:01:37
Finished restore at 31-MAY-10

RMAN> recover database until scn 574131;

Starting recover at 31-MAY-10
using channel ORA_DISK_1

starting media recovery

archive log thread 1 sequence 7 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_25/o1_mf_1_7_5zpzh95q_.arc
archive log thread 1 sequence 8 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_8_606k8n7x_.arc
archive log thread 1 sequence 9 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_9_606lkvgy_.arc
archive log thread 1 sequence 10 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_10_606mfskg_.arc
archive log thread 1 sequence 11 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_11_606ndqvj_.arc
archive log thread 1 sequence 12 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_12_606szwxo_.arc
archive log thread 1 sequence 13 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_13_606t3zs8_.arc
archive log thread 1 sequence 14 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_14_606t777d_.arc
archive log thread 1 sequence 15 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_15_606t908r_.arc
archive log thread 1 sequence 16 is already on disk as file /home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_16_606t9jd0_.arc
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_25/o1_mf_1_7_5zpzh95q_.arc thread=1 sequence=7
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_8_606k8n7x_.arc thread=1 sequence=8
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_9_606lkvgy_.arc thread=1 sequence=9
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_10_606mfskg_.arc thread=1 sequence=10
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_11_606ndqvj_.arc thread=1 sequence=11
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_12_606szwxo_.arc thread=1 sequence=12
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_13_606t3zs8_.arc thread=1 sequence=13
archive log filename=/home/oracle/oracle/product/10.2.0/db_1/flash_recovery_area/TEST/archivelog/2010_05_31/o1_mf_1_14_606t777d_.arc thread=1 sequence=14
media recovery complete, elapsed time: 00:00:06
Finished recover at 31-MAY-10

RMAN> alter database open resetlogs;

database opened.

SQL> select status from v$instance;

STATUS
————
OPEN

SQL> select group#,members,status from v$log;

GROUP#    MEMBERS STATUS
———- ———- —————-
1          2 INACTIVE
2          2 CURRENT
3          2 UNUSED

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Recovering after loss of all members of the INACTIVE redo log group

You’re attempting to open your database and receive this message

ORA-00313: open failed for members of log group 2 of thread 1
ORA-00312: online log 2 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo02.log’
ORA-00312: online log 2 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo02a.log’

The message indicates that two members of an online redo log group in your database have experienced a media failure.

To recoveer when you’ve lost all members of an inactive redo log group, perform the following steps

Verify that all members of a group have been damaged.

Verify that the log group status is INACTIVE.

Recreate the log group with the clear logfile command.

If the recreated log group has not been archived,then immediately backup up your database.

SQL> select group#,members,status from v$log;
GROUP#    MEMBERS STATUS
———- ———- —————-
1          2 CURRENT
2          2 INACTIVE
3          2 ACTIVE

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

(Here I manually deleted redolog files members of group 2)
SQL> startup
ORACLE instance started.

Total System Global Area  285212672 bytes
Fixed Size                  1218992 bytes
Variable Size              92276304 bytes
Database Buffers          188743680 bytes
Redo Buffers                2973696 bytes
Database mounted.
ORA-00313: open failed for members of log group 2 of thread 1
ORA-00312: online log 2 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo02.log’
ORA-00312: online log 2 thread 1:
‘/home/oracle/oracle/product/10.2.0/db_1/oradata/TEST/redo02a.log’

If all members of an online redo log group are damaged, you won’t be able to open your database, oracle will allow you to only mount your database.

SQL> select status from v$instance;

STATUS
————
MOUNTED

SQL> select group#,status,archived,thread#,sequence# from v$log;

GROUP# STATUS           ARC    THREAD#  SEQUENCE#
———- —————- — ———- ———-
1 CURRENT          NO           1         11
3 INACTIVE         YES          1         10
2 INACTIVE         YES          1          9

If the status is INACTIVE ,then this log group is no longer needed for crash recovery , therefore ,you can use the clear logfile command to recreate all members of a log group.

SQL> alter database clear logfile group 2;

Database altered.

If the group has not been archived, then you will need to use the clear unarchived logfile command as follows.

SQL> alter database clear unarchived logfile group 2;

Database altered.

If the cleared log group had not been previously archived, it’s critical that you immediately create a backup of your database.

SQL> alter database open;

Database altered.

SQL> select group#,status,archived,thread#,sequence# from v$log;

GROUP# STATUS           ARC    THREAD#  SEQUENCE#
———- —————- — ———- ———-
1 INACTIVE         YES          1         11
2 CURRENT          NO           1         12
3 INACTIVE         YES          1         10

SQL>