Re: Backup Controlfile and ArchiveLog

In my last email I was not talking about the blog post... that post was something entirely different that I tested last night.

Monday night we tested with shutdown immediate. It did require us to recover the online log file and open resetlogs. If I have time this afternoon then I'll do it again and post the output...

-Jeremy

On 5/4/07, Hemant K Chitale <hkchital_at_singnet.com.sg> wrote:
>
>
> I just saw your posting at
>
> http://www.ardentperf.com/2007/05/04/recovering-your-controlfile-without-a-backup
>
> You didn't actually "recover" the controlfile.
> You really "restored" it.
> You had done a shutdown abort of the database.
> The datafiles were not in sync. The Recover command looks at all the
> datafile headers and realises that some datafiles are "ahead" of the
> others. The Recover command, then, DOES need an ArchiveLog (or the
> active online redo that hadn't been archived yet -- faking it is as
> an ArchiveLog).
>
> You were testing a specific scenario where the controlfiles were
> deleted when the instance were running.
>
> Test the scenario where the the database is shutdown normal/immediate
> (or even a RECOVER has been completed without an OPEN) -- then
> restore or recreate controlfile and try a RECOVER. See if you can
> just do a CANCEL there.
>
> At 12:43 AM Saturday, Hemant K Chitale wrote:
>
> >Interesting..
> >
> >Question : In your recovery testing, what was the exact sequence ? Was
> it ?
> > a) Restore an older controlfile binary backup -- only
> > controlfile restored, datafiles being current
> > b) Issue RECOVER DATABASE USING BACKUP CONTROLFILE -- did you
> > also specify "UNTIL CANCEL" ?
> >
> >OR
> > a) Create Controlfile
> > b) Issue RECOVER DATABASE ... commands.
> >
> >
> >What if you had also restored DataFiles from the older backup ? --
> >ie even the DataFiles
> >were not "current" ? Then, if that was a Hot Backup, you would have
> >had to apply
> >some ArchiveLog(s). If it was a Cold Backup, ... (ie ControlFile
> >and DataFiles from Monday)
> >you should have been able to CANCEL and OPEN RESETLOGS without having
> >any online redo log file (as today when you do the restore, it is
> >Wednesday so your
> >ondisk online redo logs are Wednesday's files).
> >
> >Hemant
> >
> >At 10:36 PM Friday, Jeremy Paul Schneider wrote:
> >>Related to this... we were testing some recovery scenarios for a
> >>"tech night" this past monday night and walked through controlfile
> >>recovery among other things...
> >>
> >>Even if you have a clean database shutdown (immediate) and restore
> >>*only* your controlfiles, we found that you still need to process
> >>the last online redo log then open with resetlogs. If you just say
> >>CANCEL then it won't open the database. This is interesting
> >>because your datafiles do not actually need recovery. However
> >>Oracle makes you process that last online log and open with
> >>resetlogs. My theory is that Oracle doesn't actually update the
> >>SCN in the control file until it "recovers" a logfile... even if
> >>there's nothing in that logfile to actually process...
> >>
> >>FYI, we were testing on <http://10.2.0.2>10.2.0.2
> >>
> >>-Jeremy
> >
>
>
> Hemant K Chitale
> http://web.singnet.com.sg/~hkchital
> and
> http://hemantscribbles.blogspot.com
> and
> http://hemantoracledba.blogspot.com
>
> "First they ignore you, then they laugh at you, then they fight you,
> then you win" !"
> Mohandas Gandhi Quotes
> : http://www.brainyquote.com/quotes/authors/m/mohandas_gandhi.html
>
>

-- 
Jeremy Schneider
Chicago, IL
http://www.ardentperf.com/category/technical

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