RE: Fav. Urban Legend...

We'll remember that Jared when your book comes out;-)

-----Original Message-----
Sent: Monday, March 18, 2002 9:25 AM
To: Multiple recipients of list ORACLE-L

Hey, you're an author!

I expect perfection, grace and infallibility. ;)

Jared

On Monday 18 March 2002 07:33, Freeman, Robert wrote:
> And hey, it was Sunday morning at 0700 something... what do you
> expect from me anyways??? :-)))))))
>
> RF
>
> Robert G. Freeman - Oracle8i OCP
> Oracle DBA Technical Lead
> CSX Midtier Database Administration
>
> The Cigarette Smoking Man: Anyone who can appease a man's conscience can
> take his freedom away from him.
>
>
>
> -----Original Message-----
> Sent: Sunday, March 17, 2002 6:43 PM
> To: Multiple recipients of list ORACLE-L
>
> On Sunday 17 March 2002 07:53, Freeman, Robert wrote:
> > 1. You do not open the database to users until AFTER you do a backup
(hot
> > or cold, dosen't mater) at point t2.
>
> Well, yeah, that was the point. It doesn't have to be a cold backup, but
> since you can't do any work, it may as well be a cold backup.
>
> Jared
>
> > 2. There is a method of recovering a database (8i +) after RESETLOGS has
> > been
> > issued with archived redo logs. I discussed it in my DBA World Tour
> > backup and
> > recovery presentation. To do this, you MUST have the control file for
the
> > database from BEFORE the resetlogs operation, and backup of the control
> > file from AFTER the same operation. I've done this about 3 times in
>
> testing
>
> > and it works fine but it very very picky about the control file images.
> >
> > RF
> >
> > Robert G. Freeman - Oracle8i OCP
> > Oracle DBA Technical Lead
> > CSX Midtier Database Administration
> >
> > The Cigarette Smoking Man: Anyone who can appease a man's conscience can
> > take his freedom away from him.
> >
> >
> >
> > -----Original Message-----
> > Sent: Friday, March 15, 2002 7:28 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Hi Jared,
> >
> > > > * You *have* to take a COLD backup of the database after using
> > >
> > > resetlogs.
> > >
> > > > (Not required - a Hot backup and archive logs is adequate. All hot
> > >
> > > backups /
> > >
> > > > archive logs prior to that are invalid, though...)
> > >
> > > Consider the following:
> > >
> > > Time:
> > >
> > > t0: database restored
> > > t1: database opened with RESETLOGS
> > > t2: hot backup started ( database in archive log mode )
> > > t3: users input very important transactions
> > > t4: database crashes, and must be restored
> > >
> > > How will you recover the transactions from time t3?
> >
> > As long as the online redologs are available, this should be no problem.
> > I have successfully recovered databases where a log switch did not occur
> > and recovery had to use an online redo log. (I am assuming that the lost
> > datafiles will be restored from this hot backup fresh off the tapes)
> >
> > On the other hand, if the online redolog is hosed you have lost the
> > transactions anyway, _regardless_ of the fact that a Cold backup was
>
> taken.
>
> > Then you will have to go back to the _previous_ incarnation and redo the
> > restore and then perform a ccf/resetlogs (i.e. back to square one). If
> > you have a Cold backup, you restore the cold backup and go on with life.
> > I.e. in both cases (availability of cold or hot backup, lost online redo
> > log), you have lost transactions...
> >
> > Additionally, with a Hot backup and depending on what was lost, you can
> > at least perform tablespace/datafile recovery . With a cold backup, you
> > will have to restore the whole database....
> >
> > The point I was trying to make was that a Cold backup after a RESETLOGS
> > does not serve anything. Maybe there is still a gotcha I have not been
>
> able
>
> > to figure out, so Backup/restore Gurus: take a bash at this logic! I
> > would love to be corrected.
> >
> > (Btw, the previous recovery scenario was on 7.3.4 - things could have
> > changed since, and I have not been able to test that out...)
> >
> >
> > John Kanagaraj
> > Oracle Applications DBA
> > DBSoft Inc
> > (W): 408-970-7002
> >
> > Grace - Getting something we don't deserve
> > Mercy - NOT getting something we deserve
> >
> > Click on 'http://www.needhim.org' for Grace and Mercy that is freely
> > available!
> >
> > ** The opinions and statements above are entirely my own and not those
of
> > my employer or clients **

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Author: Jared Still
  INET: jkstill_at_cybcon.com

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