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This article will explain in detail the example analysis of redo file corruption. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

The first situation:

Asm storage method. During the database open step, a disk group is prompted that an online log cannot be archived and a file cannot be written. In this case, the unarchived redo log is the log that needs to be archived at startup.

1. Make sure the filing space is full.

If the alert log prompts that there is no target space available, you need to consider this first

two。 If the space is freed (deleted using rman), it still cannot be started

The corresponding online log needs to be cleared.

Alter system clear logfile group 2

Or: alter system clear unarchived logfile group2

3. After startup, fully back up the database

Rman > backup database plush archivelog to destination='/oracle/dbbackup'

The second situation:

In the case of an ordinary single instance, server restart cannot be opened, indicating that an online log cannot be found and cannot be opened. After starting to mount status, query v$log and find that the status is current:

The alert log has the following error:

ORA-00313: open failed for members of log group 4 of thread 1

ORA-00312: online log 4 thread 1:'/ home/oracle/oradata/orcl/redo04B.log'

ORA-27037: unable to obtain file status

Linux-x86_64 Error: 2: No such file or directory

Check the corresponding directory file, and the file does exist.

Alter database open; prompt that crash recovery is required for the database

Attempt to close the redo4.log file corresponding to the database copy, but cannot copy it.

The database is not backed up and needs to be recovered abnormally.

Alter database mount

Recover database until cancel;-prompt that you need to open it in resetlogs mode

Alter database open resetlogs;-hint that datafile 1 needs further recovery

Recover datafile 1;-- back to the prompt that the redo04B.log file cannot be read

Alter system set "_ allow_resetlogs_corruption" = true scope=both

Shutdown immediate

Alter dtabase mount

Recover database until cancel

Recover datafile 1

Alter database open

At this time, there is an ORA-00600: internal error code, arguments: [4194] error in alert, which is caused by the inconsistency between the database in undo and the actual data.

Rebuild-undo can solve this problem

Create undo tablespace undotbs2 datafile'/ u01 size oracledata size undotbs201.dbf'Universe 10G autoextend on next 100m oracle 20G

Alter system set undo_tablespace=undotbs2 scope=both

Shutdown immediate

Startup

-full backup of the database

Rman > backup database plush archivelog to destination='/dbbackup/'

At this point, the database can be started and accessed normally, and some data may be lost.

If some table queries indicate an ora-01555 error, you can handle it by ignoring the corresponding rollback segment

Alter system set "_ corrupted_rollback_segments" ='_ SYSSMU9_1790233411 $'

If you prompt that the initialization parameters cannot be modified, you need to do the following

Alter system set "_ corrupted_rollback_segments" ='_ SYSSMU9_1790233411 $'scope=spfile

Shutdown immediate

Startup

This is the end of this article on "sample analysis of redo file corruption". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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