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Re: Newbie backup question

From: Howard J. Rogers <howardjr_at_www.com>
Date: Sat, 10 Mar 2001 10:42:54 +1100
Message-ID: <3aa96a4d@news.iprimus.com.au>

"Brian Dick" <bdick_at_home.com> wrote in message news:oK9q6.13486$PR.91352_at_news1.wwck1.ri.home.com...
> Now we're getting somewhere. I'll read up on the CONSISTENT=YES parameter.

When you do, do make sure you realise the implications of it. Namely, that you are asking for a read-consistent image of the entire database to be created. Firstly, that's an ambitious ask. You'd better have the mother of all rollback segments ready to handle the task. And you'd better provide free Valium to your Users as day after day their backup script fails with 'ORA-1555 Snapshot Too Old' error messages (and yes, there are scripts available at www.ixora.com.au to prevent snapshot too olds, but they work simply by causing rollback segments to balloon in size).

I'm not saying it can't be done, but export and import are useful adjuncts to a physical backup. I'd never trust them as my sole source of reliable backups for a production database.

> So would my restore script do something like the following.
>
> 1) Delete all old (corrupt) files from the database directory.
> 2) Create a new database.

I thought you wanted 24 by 7?? Any idea how long it takes to create a new database (don't forget you'll have to re-run catalog.sql and catproc.sql, and that can take at least 15-20 minutes on good hardware)? Anyway, theoretically, once the new database has been created, then all you'd really need to do is run import, since the dump file contains instructions to re-create all tablespaces, users, privileges, procedures, packages, tables, indexes etc etc etc.

This might be a workable solution, but you'll have to test it to destruction before relying on it (obviously), and even then, it's not going to work 100% of the time.

Regards
HJR
> 3) Create the schema name and grant appropriate authorities.
> 4) Import the backup copy of the database.
> 5) Create other users and grant appropriate authorities.
>
> "Tomasz Olczak" <t.olczak_at_wp.pldonotreply_at_interbulletin.bogus> wrote in
> message news:3AA90A3E.4EC50F77_at_interbulletin.com...
> > Brian,
> >
> > If you need 24/7 database availability and you cannot afford loosing any
> transactions in case of failure you have to switch the database to
> ARCHIVELOG mode before you can start making "hot backups" (i.e. taking
> backups while the database is up and running).
> > However if you don't want to deal with ARCHIVELOG mode issues and
> potential loss of some reasonable number of transactions (e.g. one day
> transactions if you would do a backup everyday) does not terrify you can
 use
> Export utility with CONSISTENT=YES parameter for dumping all the schema or
> database data into a file in consistent state even while the database is
> open and being used. You can then use this file to recreate all the data
 in
> the database (so called "import").
> > However the recommended solution is running a production database in
> ARCHIVELOG mode and using RecoveryManager for backup and recovery
> procedures.
> > I would suggest you to register for technet.oracle.com and go to:
> >
>

 http://technet.oracle.com/docs/products/oracle8i/doc_library/817_doc/server.
> 817/a76955/toc.htm
> > for information on Export utility.
> >
> > Regards,
> > Tom Olczak
> >
> > "Brian Dick" <bdick_at_home.com> wrote in article
> > <D66q6.13243$PR.91127_at_news1.wwck1.ri.home.com> :
> > >I am mainly an application developer, but I've been tossed onto a
 project
> > >that needs a quick solution for backup. We have no "real" DBA, just me
 as
 a
> > >"de facto" DBA.
> > >
> > >The project uses Oracle V8.1.6 as an imbedded database, so it needs to
 run
> > >almost entirely unattended and 24x7. The database is relatively small
 and
 is
> > >configured to run in NOARCHIVE mode.
> > >
> > >But the users of the system do want to be able to frequently run a
 script
> > >that takes a full backup of the database. If the system incurrs a media
> > >crash, then the users would run a script for a restore from the backup.
 Loss
> > >of data from the time of backup to the time of restore is NOT an issue.
> > >
> > >I've read the Oracle8i Backup and Recovery Guide a couple of times, and
 I
 am
> > >confused with all of the options available. I think my requirements are
> > >fairly simple and all of these ARCHIVE/NOARCHIVE,
 consistent/inconsistent,
> > >complete/incomplete decisions really blur the picture.
> > >
> > >I know the above scenario is less than optimal, but I have to play with
 the
> > >cards I have been delt. We plan to have a robust backup/recovery
 process
 in
> > >the next version of our system (promise <g>).
> > >
> > >Later,
> > >BEDick
> > >
> > >
> > >
> >
> > _______________________________________________
> > Submitted via WebNewsReader of http://www.interbulletin.com
> >
>
>
Received on Fri Mar 09 2001 - 17:42:54 CST

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