Corrupted Redolog file and no backup

[bang_dba]

hi,
One of my Redolog group is corrupted and unfortunately
it has only one member. My database is running in
Archivelog mode, but i don't have any old backup. How
can i open my database. I guess now i cannot do incomplete
recovery becoz i don't have any old backup. But all my
datafiles are intact. What can i do in this situation.

Regards

[Sameer]

Try clearing the logfile..

Execute...

ALTER DATABASE CLEAR LOGFILE GROUP n;
or
ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP n;

if it works successfully, take the hot/cold backup immediately..

[adewri]

do what sameer said...

[adewri]

is the whole group corrupted or one of the files ??
what does your alert log file say ??

if it gives error then...

try to shutdown the database normally

startup mount and then try
ALTER DATABASE CLEAR UNARCHIVED LOGFILE '/u6/oradata/sid/redo_1a.log';

then try to open it and then do a nomal shutdown...
take a backup...

[bang_dba]

hi
i am getting following errors


SQL> alter database clear logfile group 2;
alter database clear logfile group 2
*
ERROR at line 1:
ORA-01624: log 2 needed for crash recovery of thread 1
ORA-00312: online log 2 thread 1: 'D:\ORADATA\LOG\LOG02.LOG'


SQL> alter database clear unarchived logfile group 2;
alter database clear unarchived logfile group 2
*
ERROR at line 1:
ORA-01624: log 2 needed for crash recovery of thread 1
ORA-00312: online log 2 thread 1: 'D:\ORADATA\LOG\LOG02.LOG'

[bang_dba]

hi,

I tried this option as well....
but it is not workingSQL> alter database clear logfile group 2 unrecoverable datafile;

SQL>alter database clear logfile group 2 unrecoverable datafile
*
ERROR at line 1:
ORA-01624: log 2 needed for crash recovery of thread 1
ORA-00312: online log 2 thread 1: 'D:\ORADATA\LOG\LOG02.LOG'


I think i this situation it is not possible to recover the database..

[adewri]

if its not then try shutting it down...
and do as i told you earlier....

im waiting for ur reply ....

[nabeel]

How many groups you have? and How many members? If the DB is running then add new groups with 2 members... and then switch the log files till it uses the new one and then drop the old one... shutdown the DB take care complete backup...


Hope this is Helpfull

[nabeel]

Additional information:
Because log group 2 is the current log group, it will not have been archived. Using the CLEAR LOGFILE command is of no use because:

SQL> alter database clear unarchived logfile group 2;
ORA-01624: log 2 needed for crash recovery of thread 1
ORA-00312: online log 2 thread 1: 'disk1/archive/log2a.rdo'

Try Performing Incomplete recovery therefore, First you must note the current log sequence number by issuing this statement

SQL> select * from v$log;

Use the ALTER DATABASE DROP LOG GROUP and ALTER DATABASE ADD LOG GROUP commands to create the log files manually. Because you performed incomplete recovery, the database should now be backed up.

[bang_dba]

nabeel,
As i don't have old backup, now i can't do anything.

I think, Nothing can be done at this point.