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 Mon Aug 27 2001 - 15:42:56 CDT
