How do I recover a corrupt redo log file?

Recovering After the Loss of All Members of an Online Redo Log Group

Locate the filename of the lost redo log in V$LOGFILE and then look for the group number corresponding to it.
Determine which groups are active.
If the affected group is inactive, follow the procedure in Losing an Inactive Online Redo Log Group.

What will happen if redo log file was corrupted?

A redo log file might become corrupted while the database is open, and ultimately stop database activity because archiving cannot continue. In this situation the ALTER DATABASE CLEAR LOGFILE statement can be used to reinitialize the file without shutting down the database.

How do I restore a redo log in Oracle?

Step-By-Step Guide

Run the following code to check to see what log is currently in use. set lines 180.
Make a note of the current log file group.
Drop and recreate logfile group 1.
Repeat the process for logfile group 2 and 3.
Switch log file group to free up log file group 4.
Drop and recreate logfile group 4.

What is redo log file in Oracle?

Redo log files are operating system files used by Oracle to maintain logs of all transactions performed against the database. The primary purpose of these log files is to allow Oracle to recover changes made to the database in the case of a failure.

How do you know if a redo log is corrupted?

Find the corrupted group# from v$log; Select group# from v$log;

Clear the archived group(corrupted) (alter database clear logfile group
If could not clear archived redolog then clear the redolog without archiving using(clear unarchived ) alter database clear unarchived logfile group group#

Can we delete redo log files?

It is permissible to drop redo log files so that a multiplexed redo log becomes temporarily asymmetric. For example, if you use duplexed groups of redo log files, you can drop one member of one group, even though all other groups have two members each.

How do I find the current redo log file?

The V$LOGFILE view can be used to find the datafiles for the redo logs.

How do you calculate redo log?

I discovered that I have 15 groups of 2 GB, so the redo log group size is 30 GB. Oracle says that “In general we recommend adding an additional 30% on top of the peak rate”, so that would mean I am expected to have 245mb/s*1.3 = 318.5 MB/S.

What does redo log file contain?

The most crucial structure for recovery operations is the redo log, which consists of two or more preallocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has an associated redo log to protect the database in case of an instance failure.

How do I get rid of standby redo logs?

How to drop the standby redo logs

Enviroment.
SET STANDBY_FILE_MANAGEMENT=’MANUAL’
Drop SRL On Standby.
SET STANDBY_FILE_MANAGEMENT=’AUTO’
Enable MRP.
Enviroment.
SET STANDBY_FILE_MANAGEMENT=’MANUAL’
Drop SRL On Standby.

Can I delete Oracle redo logs?

In case you want to clear out your Redo Log files in a situation of an unexpected failure or corruption, you can use the alter table clear logfile command as follows: Sql>alter database clear logfile group 3; Clearing an Unarchived Redo Log File.

What to do if your redo log file is corrupted?

Clearing a Redo Log File A redo log file might become corrupted while the database is open, and ultimately stop database activity because archiving cannot continue. In this situation the ALTER DATABASE CLEAR LOGFILEstatement can be used to reinitialize the file without shutting down the database.

How to fix online redo log corruption in Oracle?

3- Found an additional clause to force the CLEAR. SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 4 UNRECOVERABLE DATAFILE ; Database altered. 4- Online redo log group is now clear but keep in mind that we don’t have that archive log (464704) and recoverability is compromised at this point.

How to clear an unarchived redo log in Oracle?

If you clear an unarchived redo log file, you should make another backup of the database. If you want to clear an unarchived redo log that is needed to bring an offline tablespace online, use the UNRECOVERABLE DATAFILE clause in the ALTER DATABASE CLEAR LOGFILE statement.

What does alter database clear unarchived logfile Group 3 mean?

ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3; This statement clears the corrupted redo logs and avoids archiving them. The cleared redo logs are available for use even though they were not archived. If you clear a log file that is needed for recovery of a backup, then you can no longer recover from that backup.

How do I recover a corrupt redo log file? Recovering After the Loss of All Members of an Online Redo Log Group Locate the filename of the lost redo log in V$LOGFILE and then look for the group number corresponding to it. Determine which groups are active. If the affected group is inactive, follow the…