Re: Query Database while shutdown in progress

  • From: "Andrew Kerber" <andrew.kerber@xxxxxxxxx>
  • To: robertgfreeman@xxxxxxxxx
  • Date: Wed, 27 Jun 2007 14:12:45 -0500

The last time I checked, admittedly in the 8.1.7 world, oracle stated that
you could end up with file corruption on a shutdown abort (note that is
could, not would, I never had it happen),  If they have changed this and now
say that a shutdown abort is as safe as a shutdown immediate, I have not
heard it.  Does anyone have a statement from oracle to that effect?

What happens if you have datafiles in backup mode and you try and do a
startup force?



On 6/27/07, Robert Freeman <robertgfreeman@xxxxxxxxx> wrote:

 On 6/27/07, Andrew Kerber <andrew.kerber@xxxxxxxxx> wrote:

> Sometime shutdown abort is necessary.  However, its not recommended.  I
> would rather not risk having to recover a database w/o a good reason.  If
> all that is needed is to monitor a shutdown immediate. there are a lot of
> ways to handle that.  If  nothing else, you can tail the alert log, and see
> the id thats keep the instance form shutting down, then kill that session.
> That would be much safer than an abnormal termination of the instance.
>

I agree with Jared, whats up with this? Yes, a shutdown abort assures that
you will be doing crash/instance recovery, but so what? If you are truly
concerned about that, do a checkpoint before you do the shutdown abort
(assuming that does not take forever). In what cases will a shutdown require
media recovery? I know of none unless you are planning on rm'ing a bunch of
datafiles afterwards.

One of the beauties of Oracle, and a fact that seems little known, is the
rule with regards to checkpoints and redo logs. Everyone knows that a redo
log can not be reused in ARCHIVELOG mode until the archived redo log is
created. What seems less known is the rule that an online redo log can not
be reused until all dirty blocks associated with that online redo log have
been checkpointed and written to the datafiles. Thus, shutdown abort should
NEVER lead to a media recovery.

I will say, as a point of caution, that back in the 7.x days, there was a
bug that I discovered that would cause you to have to do media recovery
after a shutdown abort. So if you are running 7.x then be careful about a
shutdown abort.

RF

Robert G. Freeman
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Andrew W. Kerber

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