Re: exp and archive available.... recover table

On Jul 13, 12:00 pm, Alexander Skwar <alexan..._at_skwar.name> wrote:
> Preston <dontwant..._at_nowhere.invalid> wrote:
> > Alexander Skwar wrote:
>
> >> Hello.
>
> >> On 11 Jul., 21:59, "rogergor..._at_gmail.com" <rogergor..._at_gmail.com>
> >> wrote:
> >> > On Jul 11, 3:46 pm, "rogergor..._at_gmail.com" <rogergor..._at_gmail.com>
> >> > wrote:
>
> >> > > If you really need help, go to $ORACLE_HOME/rdbms/demo/ and look
> >> > > at and play with the 4 case*.rcv files.
> >> [...]
> >> >http://www.psoug.org/reference/rman_demos.html
>
> >> I now had a chance to check out those pointers. First of, they really
> >> look interesting and can teach me quite a bit. But they just deal
> >> with the "simple" case of having to backup/recover Oracle databases,
> >> don't they? They don't deal with "external" directories, do they?
>
> > Congratulations Alexander, you've managed to generate two of the most
> > laughable threads I've seen in usenet in a long time ;-)
>
> Thanks. Glad to have made you happy/laugh. I hope that you at least
> had a good one :-)
>
> > A few bits of advice, if I may. Firstly, ditch Google Groups & use a
> > usenet client & account instead (I recommend XanaNews &
> >http://news.individual.net).
>
> *LOL* :) Congrats to you as well - you managed to fetch the "only" post
> I sent over GG :) Normally, I use individual.de and am happy to pay the
> 10€ for a very long time now. And, as you can see from my headers, I use
> a (somewhat) decent NUA ;) Because of the recent change reg. cancel and
> supersedes, I now only use individual - besides the
>
> > Then you can create a killfile & never
> > have to see Sybrand's arrogant tripe ever again (apart from when others
> > quote it, obviously).
>
> "Obviously"... I begin to hate that word - for "obvious" reasons... *g*
>
> > Secondly, one of the usenet rules some posters adhere to is to never
> > admit it when you're wrong. You seem like a decent, intelligent chap,
> > so do the decent, intelligent thing, & stop replying to posts about
> > whether exp is or isn't a backup.
>
> Fine. Will do.
>
> > Exp allows you to recover data that
> > would otherwise be lost & is therefore, by definition, a backup. It's
> > obviously not the *best* way to backup Oracle data by any means, but
> > nobody's arguing otherwise.
>
> You're right. And I also would not say that an exp "backup" is suited
> in the most situations. Only in some rare situations it might be usable,
> after verifying that it doesn't cause problems.
>
> > As for your specific problem, RMAN can't backup external files.
>
> Now, finally, an answer. Gosh. That was hard. ;)
>
> > It's
> > hard to tell without knowing your application, but could you run a
> > script to lock the vault files & directories (i.e. make them read only)
> > before starting a hot backup, so in the unlikely situation that a user
> > does try to save a change, they're blocked from doing so until the
> > backup finishes & the files are unlocked?
>
> I don't know if that's possible, but that's something I'll try to
> find out. Gotta ask the UGS people what happens, when the filesystem
> is now all of a sudden read-only.
>
> > If so, you wouldn't need to
> > shutdown the database, & RMAN would be your best solution.
>
> Yep.
>
> I now "played" a bit and am (again *G*) not so convinced that RMAN would
> be my best solution. What advantage does RMAN offer over backing up the
> "hot" database .dbf files in combination with the archived redo log files?
> I'm only interested in doing backup to disk. At least for now.
>
> What I'm now considering to do is, that I'd copy all the .dbf files and
> also the redo log files. When I have the archived redo log files available,
> I am able to do a media recovery, aren't I? And I (might) need to do a
> media recovery, when I try to startup the database and give it .dbf files,
> which are "hot". Or am I overlooking something again?
>
> I guess the advantage in RMAN would be, that I could do everything
> (restore & recover) from one interface. And, if configured properly, I
> also could control backup to/restore from tape.
>
> > Alternatively you could do the vault backup first, then RMAN, but if
> > you need to restore, do an incomplete (Point-In-Time) recovery up to
> > the time of the vault backup. This would give you a consistent
> > database, albeit at the possible expense of a few transactions.
>
> I think that this is actually the way that I'll be going.
>
> Alexander Skwar- Hide quoted text -
>
> - Show quoted text -

> What I'm now considering to do is, that I'd copy all the .dbf files and
> also the redo log files. When I have the archived redo log files available,
> I am able to do a media recovery, aren't I?

No you aren't. You are copying datafiles without putting tablespaces in backup mode.
If you put your tablespaces in backup mode when you cp files, Oracle will change the redolog mechanism, and log the complete block, instead of only the changed bytes.
RMAN is much smarter at this, so you won't need to put the tablespace in backup mode.
Cp a file on the O/S without taking any special precautions will hose your database.
Did you ever read the Concepts manual? Or do you already know 'everything'? Or do you just hack away and hope no one will notice? I really don't envy your company.

--
Sybrand Bakker
Senior Oracle DBA