Re: archivelog v/s nonarchivelog

Brian Peasland <dba_at_remove_spam.peasland.com> wrote in message news:<3F311F7F.1AAE9402_at_remove_spam.peasland.com>...
> It sounds like reading the Oracle docs would be a great idea
> (http://tahiti.oracle.com).
>
> > what is the major decision factor in deciding whether DB should be in
> > Archivelog mode or NonArchivelog mode? What are tradeoffs for each of
> > the above modes?
>
> If you are running in NoArchive mode, then you can only restore up to
> your last cold backup. You cannot take hot backups either.
>
> Running in Archive mode lets you take hot or cold backups. It also lets
> you restore from that backup and roll forward all transactions that have
> taken place since that backup. The "downside" is that there can be a
> performance issue in copying those transactions to the archive log
> destination. IMO, the downside isn't that much and archive mode is the
> way to go for most databases.
>
> > Upto what point after (crash or media failure) can I recover my DB in
> > either of the modes?
>
> For a crash, you can recover all transactions that were committed before
> the crash, no matter which mode.
>
> For a media failure, see what I've written above.
>
> > Example: Your last backup was 09:00 am and then DB crashes at 06:00pm
> > (same day). Taking this example into consideration, upto what point
> > can I restore my DB?
>
> See above.
>
>
> HTH,
> Brian

In honor of a post Howard Rogers posted some time ago,

if the size and number of online redo logs is such that they are not cycled during the day (since the last hot backup), one could potentially recover up to the last transaction, applying the (stale) online redo logs.

I've never tried it that way, but I certainly have applied what was an online redo log to obtain the message "media recovery complete".

Pd Received on Wed Aug 06 2003 - 16:33:22 CDT