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Re: Backup trends (2): HOT or COLD

From: Paul Drake <drak0nian_at_yahoo.com>
Date: 5 Apr 2004 18:50:22 -0700
Message-ID: <1ac7c7b3.0404051750.270d43ac@posting.google.com>


"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message news:<406e65bd$0$4543$afc38c87_at_news.optusnet.com.au>...
> "Bob Jones" <email_at_me.not> wrote in message
> news:LDnbc.23629$He5.450838_at_bgtnsc04-news.ops.worldnet.att.net...
> >
> > "Sybrand Bakker" <gooiditweg_at_sybrandb.demon.nl> wrote in message
> > news:iu7r60pn591202gj49596rvg82s32qr7gq_at_4ax.com...
> > > On Fri, 2 Apr 2004 07:37:30 +0000 (UTC), Lucyna Witkowska
> > > <ypwitkow_at_nospamcyf-kr.edu.pl> wrote:
> > >
> > > >Sorry, I made a stupid version error and discussion "went to raspberry
> > > >bushes" (as we say in Poland).
> > > >So I try again. ;-)
> > > >Oracle 8.1.7.2 (version supported by the application developer).
> > > >Is there any admin (8.1.7.2, 8.1.7.4) that rely only on RMAN warm
> backups?
> > > >
> > > >Greetings,
> > > >Lucyna Witkowska
> > >
> > > Sure, why not.
> > > RMAN is much more stable than any home grown korn shell script.
> > > For some time I'm trying to get the home grown scripts out of the
> > > window. They are too inflexible and many of them require maintenance
> > > when datafiles are added. RMAN doesn't need that.
> > >
> > >
> > > --
> > > Sybrand Bakker, Senior Oracle DBA
> >
> > I have to disagree. We have been using shell scripts to backup for years
> and
> > never have any problem. They do not require maintenance if datafiles are
> > added. I have never used RMAN. Does it backup files with OS copy, or
> Oracle
> > special commands to backup only the data not the empty space in the data
> > files? I would consider RMAN only if the later is true.
>

<snip>

> It's taken a while, but I think more and more people are coming to the
> conclusion that RMAN is not only a viable backup and recovery tool, but is
> actually rather good these days. (If you're still stuck on 8.0, I can
> understand your reluctance to use it rather better!).
>
> Regards
> HJR
Howard,

You've probably covered this elsewhere before, but I think that its worth restating ...

If I could add one more selling point for RMAN, it would be block checking.
With RMAN, you don't have to run dbv against the datafiles in the (physical) backup set, and you don't have to apply the archived redo logs against a standby database just to make sure that one of the logs is not corrupted.

I have only seen an archived redo log corrupted once, but that was more than enough times. It caused an incomplete recovery scenario, where complete recovery should been possible (yes, the archived redo logs were duplexed, but this particular failure mode found a way around that - makes me think of Jurassic Park - nature found a way around the design constraints).

The corrupt archived redo log was not Oracle's fault, it was a hardware issue (RAID controller). It certainly makes sense though - that the time that you need to perform media recovery is when its most likely that you'll find a corrupt archived redo log.

Paul Received on Mon Apr 05 2004 - 20:50:22 CDT

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