Using _ALLOW_RESETLOGS_CORRUPTION in case of corruption: How to recover & open the database ?

March 20, 2018

Not your everyday task, yet, when nothing else you could do with a database that won’t start, give it a try. If you have valid Oracle support, then execute only after Oracle confirms.

Please note, there are no guarantees that using the “_ALLOW_RESETLOGS_CORRUPTION” hidden parameter will bring your database up and running. For example, I have made several attempts to duplicate a database in the same machine, few of the exercises were like following:

At home, I copied .dbf files from a live database and created a new database using the “_ALLOW_RESETLOGS_CORRUPTION” which was successful, when the same approach failed without any hopes on my work laptop where I have the same to upgraded instance.

Other hand whenever I copied the .dbf files from a shutdown database and tried to create a standby database, it always succeeded with “alter database open resetlogs”

So, don’t be over confident about recovering a database using “another” hidden parameter. If you are lucky, you may, on the other hand ONLY a proper backup will help you to recover from a significant crash.

So, start backing up your database on regular intervals. I suggest RMAN with archivelogs which helps you to backup the database without downtime.

Tales From A Lazy Fat DBA

Recently while opening a TEST RAC database we found the database down and was not available, we tried to start the database but received communication errors and left us clueless. Due to some urgent POC activity scheduled on the database we started investigating the root cause right away for error.
ORA-03113: end-of-file on communication channel

[oracle@testdbdixit ~]$ sqlplus / as sysdba
SQL*Plus: Release Production on Thu Feb 26 01:04:23 2015
Copyright (c) 1982, 2013, Oracle. All rights reserved.

Connected to an idle instance.
SQL> startup
ORA-03113: end-of-file on communication channel

We tried to open the database in MOUNT mode and it reached to phase easily without any error.

ORACLE instance started.

Total System Global Area 1.6034E+10 bytes
Fixed Size 2269072 bytes
Variable Size 2449473648 bytes
Database Buffers 1.3556E+10 bytes
Redo Buffers 26480640 bytes
Database mounted.

But the recovery of any kind got failed because of the…

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