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Re: online-backups

From: Jay Hostetter <jhostetter_at_dande.com>
Date: 1997/04/21
Message-ID: <335B24DA.684A@dande.com>#1/1

OHEARN wrote:
>
> Is there a way to do on-line backups(Hot Backups) without ever shutting
> the database down. Is there a way to turn the archive logs on and off
> without taking the database down.

Allen Kirby wrote:
>
> Laurie D. Miller wrote:
> <snip>
> > Yes, hot backups can be executed while the instance is up. In fact,
> > that is why they are called hot backups. Generally, you take
> > a tablespace offline, backup it up, and put back online. Also,
> <snip>
>
> Laurie,
> Hot backups don't take the tablespaces offline. It just stamps the
> header
> of the datafile with the redolog sequence number so it knows where to
> start recovery if that backup copy is used for a restoral. Oracle
> continues to write to the datafile during the backup procedure. When
> you are finished, it updates the header once again (see 'alter
> tablespace
> begin|end backup' from sqldba). This is no additional overhead required
> internally by Oracle during a hot backup.
> --
> ---
> Allen Kirby AT&T ITS Production Services
> akirby_at_att.com Alpharetta, GA.

Also, note that archiving must be enabled to do this. As far as the second part of the original question about enabling/disabling archiving on the fly -- If Oracle allowed you to do this, you would end up with an unrecoverable database. (e.g. You turn archiving off (on the fly), load data, turn it back on (on the fly), then your database crashes before the next backup. Now you restore files from your original backup and recover to the crash. You would be missing all transactions in the database while archiving was off.) Of course, if you don't do your backups after the shutdowns, you're still in the same boat. The UNRECOVERABLE keyword for creating indexes and tables, and for direct path loads is as close as you'll get to on-the-fly enabling/disabling of archives.

-- 
*************************
Jay Hostetter
D. and E. Communications
Ephrata, Pa.  U.S.A
*************************
Received on Mon Apr 21 1997 - 00:00:00 CDT

Original text of this message

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