Re: Mimic incomplete recovery - Noarchivelog Mode

Hi Nick,

I agree this can all appear somewhat odd but we've got to make it a tad difficult else everyone will want a go :)

When you open the database with RESETLOGS, you effectively blow away any online redo logs and reset the database to a new incarnation. Typically you would only do such a thing when attempting an incomplete recovery as by definition you would have lost data (else why blow away the current redo log). Therefore there is a "flag" set in the control file that only permits such an operation when all datafiles are in sync *after the successful completion of an incomplete recovery* after which time the flag is reset. No incomplete recovery, no resetlogs.

However, the other scenario when you may want to perform such an operation is when performing a restore recovery with a NOARCHIVELOG database without the restore of the redo logs. You want to blow away the redo logs from the point of time of backup because you have no such backups of the redo logs. Problem is this damn flag in the control file. It will insist you only perform resetlogs after the successful completion of an incomplete recover. Hence the "dummy recovery" which effectively just sets this flag.

It's not an issue per se but it is an extra step that needs to be performed and it does require sysdba (rather than sysoper) privileges hence why many sites with noarchivelog databases include the redo logs in the backups which can then be subsequently restored with the rest of the database and simply opened.

Cheers

Richard
"Nick" <nick_hobbs_at_hotmail.com> wrote in message news:8ca3c5c7.0210180348.6a9358ac_at_posting.google.com...
> Hi Folks,
>
> 8.1.7 on HP-UX 11i
>
> According to Oracle 8i Backup & Recovery pdf:
>
> When a NOARCHIVELOG database is restored to a new location (due to
> media failure at the original location), DBA should mimic incomplete
> recovery and cancel before opening the database with RESETLOGS
> options.
>
> Question : What does the mimic of incomplete recovery actually
> achieve? I'm told it is necessary to allow RESETLOGS when opening the
> database. Does this mean the mimic is mandatory. Since the database
> has had a full database restore and file names have been altered I'm
> unclear as to why a faxed incomplete recovery should be necessary.
>
> BTW I would test it out but I'm on DB2 at present about to move to an
> Oracle site.
>
> Any help appreciated.
>
> Regards
>
> Nick
Received on Fri Oct 18 2002 - 07:45:46 CDT