Re: Recovering database with corrupted redo log files and no good backup

On Wed, 13 Jan 1999, David Schwartz wrote:
>
> I think the subject says it all. Is it possible?
> I cannot start up my Oracle 8.0.4 database, because of an error
> indicating that the sequence in the redo log is off by a few. I don't
> really care about losing a little data.
> I've tried unsuccessfully to do an incomplete recovery. I'd at least
> like to be able to get at the data in my datafiles in some way or other.

Assuming the problem is in the automatic crash recovery routine, and assuming you have no previous backup, you have a couple options. Both of these options are last resort options, and if you have any doubts at all, you should enlist the help of Oracle Support to walk you through it.

Option 1: put the following parameter into your init<sid>.ora file:

_allow_resetlogs_corruption = true

Start up the database. When crash recovery fails, issue an "alter database open resetlogs." Export the data you need, and rebuild the database. Don't forget to remove the _allow_resetlogs_corruption parameter when you are done.

There is no guarantee this will get you anything, since the database will be coming up with all the files at different SCNs. The database might crash as soon as it opens, as transactions rolling back that were open when the database crashed try to apply themselves to blocks that don't have the proper transaction ID in the block header, because one file is older than the other.

Option 2: Data Unloader (DUL). This solution can be applied by Oracle Support in extreme business critical circumstances in which a documented Oracle bug (not the user) is at fault. Data is manually unloaded from the datafiles. using a program written yers ago. This is a very messy and undesirable solution.

--
Jeremiah Wilton http://www.wolfenet.com/~jeremiah Received on Thu Jan 14 1999 - 00:52:58 CST