Re: RMAN Backups/Recoveries

From: Ofer Razon <orazon_at_dbnet.co.il>
Date: 16 Dec 2003 00:28:48 -0800
Message-ID: <74c5bf11.0312160028.4033b249@posting.google.com>

Hi Howard.
Thanks for the reply.

I think you didn`t understand me correctly so I`ll ask it in another way :

First - Is it possible to work with RMAN in the following way :

- Make a full backup once
- From now and on - make only incremental backups
- On another server - Make a full restore once
- From now and on (Every 2 days for example) - run all the incremental

changes.
I`ll neverf open the recovered database, so practicly it`ll always be in recovery mode.

What will I do with this always-recovered DB? My storage allows my to define PITs, and then define a RW view (view = in it`s storage meaning) on this PIT so I can work on it without interfering the recovery process (on the view I can do the resetlogs and it`ll affect only this branch).

Why do I need it?
I`m looking for a way to keep an updated copy of my production copy so everytime I`ll need to do some tests, I`ll be able to define a PIT and a view and work on it.

Ofer.

"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message news:<3fde1068$0$18692$afc38c87_at_news.optusnet.com.au>...
> "Ofer Razon" <orazon_at_012.net.il> wrote in message
> news:brl15q$92s$1_at_news2.netvision.net.il...
> > Hi All.
> >
> > Using Oracle 8.1.7, I am considering the use of RMAN in order to run a
> > continous recovered DB, so I`ll do a full recovery once and then, every X
> > days I`ll run an incremental recovery for this DB.
>
>
> Do you mean recoveries or backups? If you really mean recoveries, then this
> isn't going to work. Once you've recovered a database, that's it: Oracle
> won't permit you to recover the database further. For a database to be in
> permanent recovery mode, it needs to be specially created as a standby
> database (which means mounting it with a standby controlfile).
>
> > I know that the DB will never be "open". My actual plans are to use PIT
> > disks features and open a copy of the database everytime I`ll need it,
> > without ruining the recovery process.
>
> Yikes. This is a highway to horrors. You can't do point in time recovery and
> not 'ruin the recovery process'. A point in time recovery means 'issue a
> resetlogs', at which point your database is in a new incarnation, and all
> prior backups and archives taken from the source database will be useless.
> This just isn't going to work.
>
> >
> > At first we considered using a Stand By DB, but then we`ve found that
> every
> > time we`ll add/resize a datafile we`ll have to do it on the standby too,
> so
> > we dropped this idea.
>
> Bad move. This is the only technology that will do what you want (and even
> then, every time you activate the standby database, it ceases to be able to
> be further recovered, so repeated opening of it would mean a lot of
> re-cloning work to do each time.
>
> >
> > Will RMAN solve me this problem?
>
> No.
>
> > Do you think that it is possible to run in a "continous recovery" as I
> > described?
>
> No.
>
> > BTW: I`m couting on the feature that every "incremental recovery" will
> > update only the affected blocks in the DB and won`t create the full
> datafile
> > from scratch.
>
> Irrelevant. First of all, when you perform a recovery with RMAN, you have no
> say over how RMAN will actually perform the recovery. It uses internal
> algorithms to work out the best way of effecting a recovery, and that could
> mean -as far as it is concerned- the quickest thing might be to restore the
> full backup, and then apply all archives produced since then. There's no
> guarantee that it will restore the full-apply the incrementals-apply last
> bit of archives.
>
> Second, recovery is a process with a goal in mind: get the database back up
> and running. Once it's achieved that, it stops. Forever (or until your next
> failure).
>
> What's your actual business problem that's led you to this suggestion?
> Because if we saw that, we might be able to think of something rather more
> workable for you.
>
> Personally, I can't see this ever working until you upgrade to 9i Release 2
> and implement logical standby with Data Guard.
>
> Regards
> HJR
Received on Tue Dec 16 2003 - 02:28:48 CST