How to recover from corrupt redo log file in non-archived 10g db

Hello Friends,
I don't know much about recovering databases. I have a 10.2.0.2 database with corrupt redo file and I am getting following error on startup. (db is non archived and no backup) Thanks very much for any help.
Database mounted.
ORA-00368: checksum error in redo log block
ORA-00353: log corruption near block 6464 change 9979452011066 time 06/27/2009
15:46:47
ORA-00312: online log 1 thread 1: '/dbfiles/data_files/log3.dbf'
====
SQL> select Group#,members,status from v$log;
GROUP# MEMBERS STATUS
1 1 CURRENT
3 1 UNUSED
2 1 INACTIVE
==
I have tried this so far but no luck
I have tried following commands but no help.
SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;
Database altered.
SQL> alter database open resetlogs;
alter database open resetlogs
ERROR at line 1:
ORA-01139: RESETLOGS option only valid after an incomplete database recovery
SQL> alter database open;
alter database open
ERROR at line 1:
ORA-00368: checksum error in redo log block
ORA-00353: log corruption near block 6464 change 9979452011066 time 06/27/2009
15:46:47
ORA-00312: online log 1 thread 1: '/dbfiles/data_files/log3.dbf'

user652965 wrote:
Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

Similar Messages

How to recover from one corrupted redo log file in NOARCHIVE mode?

Oracle 10.2.1.
The redo log file was corrupted and Oracle can't work.
When I use STARTUP mount, I got no error msg.
SQL> startup mount
ORACLE instance started.
Total System Global Area 1652555776 bytes
Fixed Size 1251680 bytes
Variable Size 301991584 bytes
Database Buffers 1342177280 bytes
Redo Buffers 7135232 bytes
Database mounted.
But I have some applications which are depended on Oracle can't be started.
So, I tried STARTUP open. But I got error msg.
SQL> startup open
ORACLE instance started.
Total System Global Area 1652555776 bytes
Fixed Size 1251680 bytes
Variable Size 301991584 bytes
Database Buffers 1342177280 bytes
Redo Buffers 7135232 bytes
Database mounted.
ORA-00368: checksum error in redo log block
ORA-00353: log corruption near block 497019 change 42069302 time 11/07/2007
23:43:09
ORA-00312: online log 4 thread 1:
'G:\ORACLE\PRODUCT\10.2.0\ORADATA\NMDATA\REDO04.LOG'
So, how can I restore and recover my database?
If use RMAN, how to do that?
Any help will be appreciated.
Thanks.

Hi, Yingkuan,
Thanks for the helps.
Actually, I have 10 redo log files exists. All of them are here.
I tried your suggestion:
alter database clear unarchived logfile group 4;
The error msg I got is the same as before:
SQL> alter database clear unarchived logfile group 4;
alter database clear unarchived logfile group 4
ERROR at line 1:
ORA-01624: log 4 needed for crash recovery of instance nmdata (thread 1)
ORA-00312: online log 4 thread 1:
'G:\ORACLE\PRODUCT\10.2.0\ORADATA\NMDATA\REDO04.LOG'
Compared to losing all the data, it is OK for me lose some of them.
I have more than 1 TB data stored and 99.9% of them are raster images.
The loading of these data were the headache. If I can save them, I can bear the lost.
I want to grasp the last straw.
But I don't know how set the parameter: allowresetlogs_corruption
I got the error msg:
SQL> set allowresetlogs_corruption=true;
SP2-0735: unknown SET option beginning "_allow_res..."
I have run the command:
Recover database until cancel
Alter database open resetlogs
The error msg I got is the following:
SQL> recover database until cancel
ORA-00279: change 41902930 generated at 11/05/2007 22:01:48 needed for thread 1
ORA-00289: suggestion :
D:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\NMDATA\ARCHIVELOG\2007_11_09\O1_MF_
1_1274_%U_.ARC
ORA-00280: change 41902930 for thread 1 is in sequence #1274
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: 'D:\ORACLE\PRODUCT\10.2.0\ORADATA\NMDATA\SYSTEM01.DBF'
ORA-01112: media recovery not started
SQL>
From the log file, I got the following:
ALTER DATABASE RECOVER database until cancel
Fri Nov 09 00:12:48 2007
Media Recovery Start
parallel recovery started with 2 processes
ORA-279 signalled during: ALTER DATABASE RECOVER database until cancel ...
Fri Nov 09 00:13:20 2007
ALTER DATABASE RECOVER CANCEL
Fri Nov 09 00:13:21 2007
ORA-1547 signalled during: ALTER DATABASE RECOVER CANCEL ...
Fri Nov 09 00:13:21 2007
ALTER DATABASE RECOVER CANCEL
ORA-1112 signalled during: ALTER DATABASE RECOVER CANCEL ...
Thank you very much. and I am looking forward to your followup input.

How to disable write to redo log file in oracle7.3.4

in oracle 8, alter table no logged in redo log file like: alter table tablename nologging;
how to do this in oracle 7.3.4?
thanks.

user652965 wrote:
Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

Recover from missing files(redo log file/control file) and state of the DB

Hello,
i hv go through the doc. as well. But have some doubts what will happen in each on these situations.
Pls help me to clarify these!
Scenario is like this;
hv 3 redo log files - multiplxed
hv 3 control files - multiplxed
- What will happen if 1 redo log file missing when starting the DB?
- What will happen if 1 redo log file missing when using(performing operations) the DB?
(will it recover automatically/db abort/even redo log lost will the DB run as usual... ?)
-How to recover this lost redo log?
- What will happen if 1 control file missing when starting the DB?
- What will happen if 1 control file missing when using(performing operations) the DB?
(will it recover automatically/db abort/even control file lost will the DB run as usual... ?)
-How to recover this lost redo log?
thanks

- What will happen if 1 redo log file missing when starting the DB?IF you have multiplexed the members you can drop the lost file and will be able to open the DB
What will happen if 1 redo log file missing when using(performing operations) the DB?Again if multiplexed it will drop a warinign in the alert log and contnue to write on othere members
http://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/recoscen.htm#sthref1385
- What will happen if 1 control file missing when starting the DB?Just remove the entry from the init.ora and start the DB
What will happen if 1 control file missing when using(performing operations) the DB?Will shutdown

Question about how Oracle manages Redo Log Files

Good morning,
Assuming a configuration that consists of 2 redo log groups (Group A and B), each group consisting of 2 disks (Disks A1 & A2 for Group A and Disks B1 and B2 for group B). Further, let's assume that each redo log file resides by itself in a disk storage device and that the device is dedicated to it. Therefore in the above scenario, there are 4 disks, one for each redo log file and, each disk contains nothing else other than a redo log file. Furthermore, let's assume that the database is in ARCHIVELOG mode and that the archive files are stored on yet another different set of devices.
sort of graphically:
    GROUP A             GROUP B
      A1                  B1
      A2                  B2The question is: When the disks that comprise Group A are filled and Oracle switches to the disks in Group B, can the disks in Group A be taken offline, maybe even physically removed from the system if necessary, without affecting the proper operation of the database ? Can the Archiver process be temporarily delayed until the disks (that were removed) are brought back online or is the DBA forced to wait until the Archiver process has finished creating a copy of the redo log file into the archive ?
Thank you for your help,
John.

Hello,
Dropping Log Groups
To drop an online redo log group, you must have the ALTER DATABASE system privilege. Before dropping an online redo log group, consider the following restrictions and precautions:
* An instance requires at least two groups of online redo log files, regardless of the number of members in the groups. (A group is one or more members.)
* You can drop an online redo log group only if it is inactive. If you need to drop the current group, first force a log switch to occur.
* Make sure an online redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
GROUP# ARC STATUS
1 YES ACTIVE
2 NO CURRENT
3 YES INACTIVE
4 YES INACTIVE
Drop an online redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
The following statement drops redo log group number 3:
ALTER DATABASE DROP LOGFILE GROUP 3;
When an online redo log group is dropped from the database, and you are not using the Oracle Managed Files feature, the operating system files are not deleted from disk. Rather, the control files of the associated database are updated to drop the members of the group from the database structure. After dropping an online redo log group, make sure that the drop completed successfully, and then use the appropriate operating system command to delete the dropped online redo log files.
When using Oracle-managed files, the cleanup of operating systems files is done automatically for you.
Your Database wont be affected as you can operate with 2 redo log files in each group as The minimum number of redo log files required in a database is two because the LGWR (log writer) process writes to the redo log files in a circular manner. so the process will hang becuase you are having 2 only groups if you want to remove 1 add a third one and make it the current group then remove the one you want to be offline.
Please refer to:
http://download.oracle.com/docs/cd/B10500_01/server.920/a96521/onlineredo.htm#7438
Kind regards
Mohamed
Oracle DBA

Current redo log file is lost

Hi All,
I got a scenario in which my current redo log file is lost:
Do I need to:
1)Clear log file group
(or)
2)I should perform incomplete recovery.
What are the steps I should follow to recover this current redo log file?
1)*If it is inactive* I can make use of
ALTER DATABASE CLEAR LOGFILE UNARCHIVED GROUP 2;
which will drop and recreate the log file.To recover from loss of an active online log group in NOARCHIVELOG mode:
If the media failure is temporary, then correct the problem so that the database can reuse the group when required.
Restore the database from a consistent, whole database backup (datafiles and control files) as described in "Restoring Datafiles Before Performing Incomplete Recovery". For example, enter:
% cp /disk2/backup/*.dbf $ORACLE_HOME/oradata/trgt/
Mount the database:
STARTUP MOUNT
Because online redo logs are not backed up, you cannot restore them with the datafiles and control files. In order to allow the database to reset the online redo logs, you must first mimic incomplete recovery:
RECOVER DATABASE UNTIL CANCEL
CANCEL
Open the database using the RESETLOGS option:
ALTER DATABASE OPEN RESETLOGS;
Shut down the database consistently. For example, enter:
SHUTDOWN IMMEDIATE
Make a whole database backup.
To recover from loss of an active online redo log group in ARCHIVELOG mode:
If the media failure is temporary, then correct the problem so that the database can reuse the group when required. If the media failure is not temporary, then use the following procedure.
Begin incomplete media recovery, recovering up through the log before the damaged log.
Ensure that the current name of the lost redo log can be used for a newly created file. If not, then rename the members of the damaged online redo log group to a new location. For example, enter:
ALTER DATABASE RENAME FILE "?/oradata/trgt/redo01.log" TO "/tmp/redo01.log";
ALTER DATABASE RENAME FILE "?/oradata/trgt/redo01.log" TO "/tmp/redo02.log";
Open the database using the RESETLOGS option:
ALTER DATABASE OPEN RESETLOGS;
My question is when the redo log file is current. What steps we should follow?
Best regards,
Rafi.
http://rafioracledba.blogspot.com/
2)If it is active then I can make use of below steps:

Rafi (Oracle DBA) wrote:
Hi Asif,
This link I have seen by refering to previous post.I just have a slight doubt in mind.
1)Do I need to make use of statement:
Alter database clear unarchived log file group#;
(or)
Only if your group is current(or you are not able to drop it) and is not archived then you should use above query.
We should perform incomplete recovery for this.If we have to perform incomplete recovery what are the steps I should follow?
I doubt you should be performing incomplete recovery for this.
Eg:Let us say my group 1 is dropped it has only one member and it is in active state.How to recover database?Can I get the steps?
You would not be able to drop it if it is in active state, did you meant it is corrupted? If yes then you can use below query
Alter database clear [unarchived] LOGFILE GROUP #;>
Best regards,
Rafi
http://rafioracledba.blogspot.com/
Make sure to backup your database after above activity.
Regards
Anurag

Redo log file corupted, database not getting open

I am Oracle Funda-1 student.
Have install standard Oracle 9I on Windows XP pro service pack 2.
I made some changes in sample table & given commit. So log buffer will flush to redo log file.
Then I open current redo log file from OS & selected all junk characters [select all] & deleted same. Save the file. Causing redo file size 0KB.
Then made more changes to table & issue commit. no errors ! every thing working file.
Even chked V$log & V$logfile.
Again I open current redo log file from OS & selected all junk characters [ select all ] & deleted same. Save the file. Causing redo file size 0KB.
Then issue manual log switch. Alter system switch logfile
I got disconnected from database & database was close.
When I reconnected & try to open database in normal mode. Gave error saying redolog_1.log is corrupted & needed for recovery.
Now not even allowing me clear redo group 1. with alter database clear logfile group 1. as database is not coming to open stage.
just able to mount the database. with error rdolog_1 corrupted.
Wasn't oracle suppose to be halted when very 1st time I corrupted redo log file.
Why it disconnected me & got close.
When then one use alter database clear logfile group 1.

I may try this ALTER DATABASE OPEN RESETLOGS;
As no backup & not multiplex.
Still looking for explanation why database got close down instead of getting halt.
I have found one more status in V$log, which is not given in Oracle university book or online document.
INVALIDATED
Which come as a result when oracle unable to switch to next on line group due to non availability of next group redo log physical file.
SQL> select group#,members,status from V$log;
GROUP# MEMBERS STATUS
1 1 INVALIDATED
2 1 INACTIVE
4 1 UNUSED
As matter of fact, it's only portion of a big
document which happen to cover what you are testing
in detail.
I would invest time to read the document to
understand how things work instead of getting dirty
quick answers.

Use of standby redo log files in primary database

Hi All,
What is the exact use of setting up standby redo log files in the primary database on a data guard setup?
any good documents?

A standby redo log is required for the maximum protection and maximum availability modes and the LGWR ASYNC transport mode is recommended for all databases. Data Guard can recover and apply more redo data from a standby redo log than from archived redo log files alone.
You should plan the standby redo log configuration and create all required log groups and group members when you create the standby database. For increased availability, consider multiplexing the standby redo log files, similar to the way that online redo log files are multiplexed.
refer the link,and Perform the following steps to configure the standby redo log.:-
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
If the real-time apply feature is enabled, log apply services can apply redo data as it is received, without waiting for the current standby redo log file to be archived. This results in faster switchover and failover times because the standby redo log files have been applied already to the standby database by the time the failover or switchover begins.
refer the link
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/log_apply.htm#i1023371

Hierarchial Queries and Redo log files

Hi,
I'm running a hierarchial query (start with, connect by prior, etc.).
The query takes a couple of minutes and apparently is filling up the archive files
(I assume it comes from the redo log files).
Question:
1. Does it make sense that a hierarchial query should so fill up the redo log files (It seems as if all the 'intermediate' results are being written there).
2. What do you suggest I do ??
Thanks,
David

What do you suggest I do ??Post your query and the execution plan or the trace file from tkprof.
How to do that is explained in this thread;
How to post a SQL statement tuning request HOW TO: Post a SQL statement tuning request - template posting

Redo log file

hello.............
how can we see the redo log file is empty and full. is there any view to see this.

Anand... wrote:
Hi
how can we see the redo log file is empty and full. is there any view to see this.I would definitely like to know - Why?
AnandMy reaction exactly.
To the OP: What technical or business decision will be based on knowing if a redo log file is empty or full? BTW, notice I said a redo log file, not the redo log file. There is never just one redo log file.

How to recover data from corrupt redo

Hi All,
I have one qurey regarding redo file. My database is in Noarchive mode and all redo files size is 1G, there are 3 groups and all group having 1 member each.
Now in case my all redo corrupt/dropped then can I recover my data from corrupt redo? does it mean that I can have loss of 3G data? is it?
Please update me.
Thanks...

Yes, it's true that a lost or corrupted redo log can put your entire database at risk. Please read Re: How can I get around recovering a data file that doesn't need to be?? for a recent thread on the same issue.
To summarize the options you have, in roughly descending order of desirability:
1. If you have one, restore the database from a recent cold backup.
2. If you have a recent export, rebuild your database and import your data from the export.
3. If you have no sort of backup whatsoever, attempt to open your database without the redo logs, using an undocumented startup parameter. This option is risky. It may not work at all and it may further damage your database. It's best to do this under the supervision of Oracle Support, if you have a valid support contract. Don't try this without first taking a cold backup of your database. If it does work, you must immediately take an export and then proceed to option 2 (rebuild your database and import data from export).
4. Buy a license for DUDE, or some similar product, which may allow you to recover your data from the remaining data files. This option will probably be very expensive.
5. Accept the loss of your entire database.

How to recover from deleting log file?

Hi,
In a case on Mondayitis I accidentally deleted C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_1_35N72N5G_.LOG'
and now can't start my database. (see error below)
Tue Jun 12 12:40:29 2007
Errors in file c:\oraclexe\app\oracle\admin\xe\bdump\xe_lgwr_3544.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: 'C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_1_35N72N5G_.LOG'
ORA-27041: unable to open file
OSD-04002: unable to open file
O/S-Error: (OS 2) The system cannot find the file specified.
Tue Jun 12 12:40:30 2007
ORA-313 signalled during: ALTER DATABASE OPEN...
Can someone guide me on how I can create a new log file and get my database up and running.
Thanks
Anthony

After a bit more research I fixed the problem.
But just in case anyone else does the same stupid thing - here is how I fixed it.
connect / as sysdba
RECOVER DATABASE UNTIL CANCEL;
ALTER DATABASE OPEN RESETLOGS;
And database is up and running.
Regards
Anthony

Redo log files lost in Disk Corruption/failure

DB version:10gR2
In one of our test databases, I have lost all members of a group due to disk corruption(it was a bad practise to store both members on the same filesystem)
Database is still up. We don't have a backup of the lost redo log group. Altogether we had 3 redo log groups. this is what i am going to do to fix this issue.
Step 1. Add a redo log group
ALTER DATABASE
ADD LOGFILE ('/u04/oradata/ora67tst/log4a.rdo',
   '/u05/oradata/ora67tst/log4b.rdo') SIZE 15m;Step 2. Drop the corrupted redo log group
ALTER DATABASE DROP LOGFILE GROUP 2;Is this the right way to go about fixing this issue?
The documentation says that you need to make sure a redo log group is archived before you DROP it.
When i use the query
SQL>SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
    GROUP# ARC STATUS
         1 YES ACTIVE
         2 NO CURRENT
         3 NO INACTIVE
How can i force the archiving of a redo log group 2?
Edited by: Citizen_2 on May 28, 2009 10:10 AM
Edited by: Citizen_2 on May 28, 2009 10:11 AM

Citizen_2 wrote:
How can i force the archiving of a redo log group 2?How could you archive a log group when you have lost all members of that group?
Have you checked out this documentation: [Recovering After the Loss of Online Redo Log Files|file://///castle/1862/Home%20Directories/Vaillancourt/Oracle%2010gR2%20Doc/backup.102/b14191/recoscen008.htm#sthref1872]
More specifically:
If the group is . . .      Current
Then . . .
It is the log that the database is currently writing to.
And you should . . .
Attempt to clear the log; if impossible, then you must restore a backup and perform incomplete recovery up to the most recent available redo log.
>
HTH!

Files for Mail, other apps to recover from corrupt volume?

After HD corruption on my MacBook running 10.7.4 I need to restore Mail accounts for several users, complete with mailboxes and smart mailboxes. Would appreciate if anybody can help me identify and locate what I need to recover the Mail accounts.
Also, I'd like to recover application specific info such as SN, as well as preferences.
Thanks in advance.

user652965 wrote:
Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

How to remove a redo log file

Hi Experts,
I want to remove a wrong redo log file from 10G R2 database in window.
how to do that without loss data?
my steps as
1. alter system switch logfile;
2. select * from v$log;
which ARC and sataus do I can drop redo log file based on above SQL
no archive and active status?
ALso Which account should I do above action?
fExamp, system account added redo log file, i only
can drop by system? how about sys?
Thanks help in detail steps
Jim
Edited by: user589812 on Dec 23, 2008 4:35 PM

Jim,
Check this link out for how to drop a redo log file
Make sure a redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#i1006489
SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
   GROUP# ARC STATUS
        1 YES ACTIVE
        2 NO CURRENT
        3 YES INACTIVE
        4 YES INACTIVE
Drop a redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
The following statement drops redo log group number 3:
ALTER DATABASE DROP LOGFILE GROUP 3;

How to recover from corrupt redo log file in non-archived 10g db

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