RE: Lost ofall redo logs

Thomas,

If you rely on the premise that cold backups can only be taken after a non-abort shutdown, then there is no reason to backup on-line redo logs. (If you rely on backing up redo because you do cold backups after shutdown abort, well, then we can have an argument about best practices.) In fact, given a proper backup strategy, there is no point at which you should need to restore an on-line redo log from backup, and, in fact, about any scencario I can think of, restoring online redo logs is either detrimental to, or has no impact on, your recovery.

Specifically, in the scenario you indicate, (cold backup, archive logs, rolling forward to a point in time), there is no need for the on-line redo. After restoring the datafiles, you'll need to apply your archives (which will still be valid against the incarnation of the database that you're working with), when you reach the desired point-in-time, you'll need to cancel recovery and then open reset logs. Note that this will happen regardless of whether you previously restored them from backup.

Don't backup on-line redo logs!

With cold backups, it's not necessary, with hot backups, it's not only unnecessary, it's dangerous!

-Mark

On Fri, 2002-09-20 at 12:38, Mercadante, Thomas F wrote:
> Naveen,
>
> Why NOT take the redo log files in a cold backup?
>
> If you restore these cold backup files and intend to use them, you would
> then have to open the database with the RESET LOGS option to re-create the
> redo logs.
>
> This would then invalidate all of your archive log files.
>
> And Joe - thanks! :)
>
>
> Tom Mercadante
> Oracle Certified Professional
>
>
> -----Original Message-----
> Sent: Friday, September 20, 2002 11:29 AM
> To: Multiple recipients of list ORACLE-L
>
>
> I'm not an expert so pardon me if i'm wrong.
>
> Why to copy the log files in case of a cold backup if the instance was
> shutdown cleanly(NOT ABORT)??
>
> The d/b will be consistent so we don't need the redo-log files, isn't it?
> Isn't it that the DB update all the Datafiles headers with the checkpoint
> information at the time of CLEAN SHUTDOWN so redo-logs are not required for
> a
> restore from cold backup?
>
> Though no harm in taking the log files backup too but they are not really
> needed?
>
> Regards,
> Naveen
>
> -----Original Message-----
> Sent: Friday, September 20, 2002 7:18 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Well, it didn't sound like he was using Rman (which does not backup redo
> logs). So I assumed that he was/should be using a cold-backup strategy -
> which, if it were me, would backup the redo logs.
>
> Tom Mercadante
> Oracle Certified Professional
>
>
> -----Original Message-----
> Sent: Friday, September 20, 2002 8:48 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Tom, that statement will open a can of worms(like a religion following)
> about if/when to backup redo logs. :)
>
> joe
>
>
> Mercadante, Thomas F wrote:
>
> >I agree with you Joe.
> >
> >I would *never* use an undocumented parameter unless Oracle told me to (or
> >unless I was testing something that I could recreate).
> >
> >Using these params on the advice of someone from this list is very
> >dangerous.
> >
> >The larger question is, why are the redo logs not being backed up?
> >
> >Arun, you need to establish a backup policy *immediately* so that you are
> >not being put into this position again.
> >
> >Tom Mercadante
> >Oracle Certified Professional
> >
> >
> >-----Original Message-----
> >Sent: Thursday, September 19, 2002 7:48 AM
> >To: Multiple recipients of list ORACLE-L
> >
> >
> >KG, doesn't anyone think not having a backup is a bad thing.
> >
> >You can go down that route if you wish but as I remember undocumented
> >parameters are best used with the assistance of OWS and not just used at
> >will.
> >
> >joe
> >
> >
> >K Gopalakrishnan wrote:
> >
> >>Arun:
> >>
> >>You are right. The original poster *clearly* said
> >>
> >>LOST ALL REDO LOGS
> >>NO BACKUP.
> >>
> >>In the above situation, you have to open the
> >>databases using the some special tricks and
> >>I don't think you need to go back and refer
> >>BAckup and Recovery Manuals (You can not
> >>find anything for this situation, that is
> >>another story)
> >>
> >>Those parameters will bring up the database
> >>if the database is cleanly shudowned (read:
> >>Shutdown Normal/Immediate) and you will
> >>have to do some more tricks to get the
> >>database up if it is crashed (read: shutdown
> >>ABORT).
> >>
> >>I don't think it is a bad advice..
> >>
> >>YMMV
> >>
> >>KG
> >>
> >>
> >>-----Original Message-----
> >>Chakrapanirao
> >>Sent: Wednesday, September 18, 2002 11:08 PM
> >>To: Multiple recipients of list ORACLE-L
> >>
> >>
> >>Well one I do want to make clear I have never tried to give bad advice to
> >>people.
> >>Since the user in his mail had said that he does not have a backup and
> does
> >>not have any online redo logs can you please let me know how else can he
> >>open the database, when he said he does not have a back it assumes that he
> >>does not have a os backup and also the rman backup.
> >>This might be the undocumented thing but this Is the only way it works
> >>And this had happened in one our case and the only way we could open the
> >>database is to force open the database in a corrupt mode take an export
> and
> >>import back into the new database.
> >>
> >>If you still think I am trying to give a bad advice well sorry that I am
> >>giving bad advices.
> >>
> >>
> >>-----Original Message-----
> >>Sent: Thursday, September 19, 2002 12:33 AM
> >>To: Multiple recipients of list ORACLE-L
> >>
> >>Arun, since WHEN has been using undocumented parameters the normal way
> >>of doing things, I think you need to go back and lookup backup/recovery
> >>concepts.
> >>
> >>Feel free to read both user managed and RMAN backup recovery
> >>
> >docs/scenarios.
> >
> >>You are giving bad advice to people on the list who might be new.
> >>
> >>joe
> >>
> >>
> >>Arun Chakrapanirao wrote:
> >>
> >>
> >>
> >>>The only way u can open your database is to add a parameter file
> >>>as
> >>>
> >>>_allow_resetlogs_corruption=TRUE
> >>>
> >>>_corrupted_rollback_segments= TRUE
> >>>
> >>>_offline_rollback_segments=(the rollback segment names)
> >>>
> >>>activate the database and then immediately take an export of the whole
> >>>database.
> >>>Create a new database and then import all the data to this new database.
> >>>
> >>>
> >>>-----Original Message-----
> >>>Sent: Wednesday, September 18, 2002 5:23 PM
> >>>To: Multiple recipients of list ORACLE-L
> >>>
> >>>Nop, all redo logs gone away...
> >>>
> >>>----- Original Message -----
> >>>To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> >>>Sent: Wednesday, September 18, 2002 5:43 PM
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>What about mirrored redo group members?
> >>>>
> >>>>Igor Neyman, OCP DBA
> >>>>ineyman_at_perceptron.com
> >>>>
> >>>>
> >>>>
> >>>>----- Original Message -----
> >>>>To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> >>>>Sent: Wednesday, September 18, 2002 4:30 PM
> >>>>
> >>>>
> >>>>Hi people...
> >>>>
> >>>>What to do if I have LOST ALL REDO LOGS and i don4t have any backup?
> >>>>
> >>>>Thanks in advance!
> >>>>
> >>>>:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> >>>>Gilberto Gampert Universidade de Passo Fundo
> >>>>Administrador de Banco de Dados Passo Fundo - RS - Bra5il
> >>>>gampert@upf.br http://www.upf.br
> >>>>:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> >>>>
> >>>>
> >>>>--
> >>>>Please see the official ORACLE-L FAQ: http://www.orafaq.com
> >>>>--
> >>>>Author: Gilberto Gampert
> >>>>INET: gampert_at_upf.br
> >>>>
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> >>--
> >>Please see the official ORACLE-L FAQ: http://www.orafaq.com
> >>--
> >>Author: Joe Testa
> >> INET: jtesta_at_dmc-it.com
> >>
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> >>San Diego, California -- Mailing list and web hosting services
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> >>--
> >>Author: Arun Chakrapanirao
> >> INET: ArunC_at_1800FLOWERS.com
> >>
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> >>
> >>
> >
>
>
>

-- 
--
Mark J. Bobak
Oracle DBA
mark_at_bobak.net
"It is not enough to have a good mind.  The main thing is to use it
well."
 						-- Rene Descartes
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Mark J. Bobak
  INET: mark_at_bobak.net

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