Re: shutdown immediate or abort for cold-backup?

Of course it knows how much of the update was completed... it makes the database consistent as per the last checkpoint number.

There is nothing, but nothing, that will get between you and an openable, consitstent database provided your redo logs (archived and online) are all intact.

Regards
HJR "Randy" <harrisr_at_bignet.net> wrote in message news:tom3b6fs0ftf0d_at_corp.supernews.com...
> I would appreciate it if you could clarify this for me, I don't wish to be
> argumentative, I truly want to understand.
>
> Should the server happen to be in the midst of a large update when the
> instance is aborted, per the Oracle docs, processing is immediately halted
> and uncommitted transactions are not rolled back. It seems to me that, on
> restart, SMON can indeed make the instance consistent as of the last
> checkpoint and recover with the redo log, but it would have no way of
> determining how much of that update was completed prior to the abort. I
> think, under these circumstances, there could be a loss of data.
>
>
> "Howard J. Rogers" <howardjr_at_www.com> wrote in message
> news:3b8aafa0_at_news.iprimus.com.au...
> > Remember that a record is kept all the time of which checkpoint sequence
> > numbers are issued, and to what redo log sequence they relate. SMON
> should
> > therefore be very easily able to tell that all required redo for
recovery
> of
> > an aborted mid-flight checkpoint is available in the current redo log,
and
> > perform automatic recovery itself without further intervention.
> >
> > Regards
> > HJR
> >
> > "Charles J. Fisher" <cfisher_at_rhadmin.org> wrote in message
> > news:Pine.LNX.4.33.0108271051340.9132-100000_at_galt.rhadmin.org...
> > > On Sat, 25 Aug 2001, Howard J. Rogers wrote:
> > >
> > > > Conceivably, it would be possible to abort whilst a checkpoint is
> > actually
> > > > being issued, and CKPT has only got round to timestamping half the
> data
> > > > files... that would indeed require media recovery, but once again,
> since
> > all
> > > > requisite redo is available in the current redo log, it wouldn't be
a
> > big
> > > > deal.
> > >
> > > So, has anybody ever seen this in practice?
> > >
> > > I assume that, were this to occur, Oracle would complain that
datafiles
> > > were in need of recovery and fail to start. Hopefully, the problem
could
> > > be resolved by a simple "recover automatic database" since the redo
> would
> > > be available (sans additional archived redo).
> > >
> > > It seems to me, however, that this is the ONLY case where a shutdown
> abort
> > > would result in an (immediately) unusable database assuming that the
> media
> > > is intact.
> > >
> > > If no one has ever actually seen this in the real world, then SMON
must
> > > have some way of automatically "rolling back" an in-flight checkpoint.
> > >
> > > I myself use shutdown aborts in the cluster management software for my
> > > systems, and I read earlier in this thread that Oracle-supplied HA
> scripts
> > > do the same. However, I would be hesitant to do a nightly shutdown
abort
> > > for fear of a checkpoint problem.
> > >
> > > It would be interesting to have a definitive answer to this question.
> > > It's a shame that Oracle developers don't really seem to participate
in
> > > this forum.
> > >
> >
> ---------------------------------------------------------------------
> > -----
> > > / Charles J. Fisher | A bad design with a good
> > presentation /
> > > / cfisher_at_rhadmin.org | is doomed eventually. A good
> design
> > /
> > > / http://rhadmin.org | with bad presentation is doomed
> > /
> > > / | immediately.
> > /
> >
>
> --------------------------------------------------------------------------
> > >
> > >
> > >
> >
> >
>
>
Received on Tue Aug 28 2001 - 07:53:47 CDT