RE: Killing pmon service - does Oracle backout?

When you kill PMON, Oracle might not deallocate semaphores or shared memory or even delete the sgadef.dbf file. Usually it does that. However shutdown abort is much more feasible to have that done.

As an advice I usually issue an alter system checkpoint and then the shutdown abort, if I have to do it.

Regards.

> -----Mensaje original-----
> De: Stephane Faroult [SMTP:sfaroult_at_oriole.com]
> Enviado el: martes 16 de enero de 2001 20:25
> Para: Multiple recipients of list ORACLE-L
> Asunto: Re: Killing pmon service - does Oracle backout?
>
> "Barker, Tony" wrote:
>
> > Hi!!,
> >
> > I recently hosed our test system and could not get into any
> utility
> > applications (SQLPLUS, SVRMGRL, ..) and I needed to bring down some hung
> > instances. (The system is Sun Solaris release 2.6 using Oracle 8.1.6) I
> > ended up canceling the PMON task of the various instances to get them to
> > come down. They all terminated and I was sure that I was going to have
> to
> > do a recovery to get them to come back up. To my surprise all the
> instances
> > came up fine after getting everything functionable.
> >
> > Does anyone know what happens when you cancel PMON that allowed
> this
> > to happen? Did SMON clean things up before the instances terminated? I
> > hope I don't have a false sense of comfort!?
> >
> > Thanks in advance for your input!!!
> >
> > Tony Barker
> > DBA - State of Indiana
> > tbarker_at_doit.state.in.us (317)232-0719
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Barker, Tony
> > INET: tbarker_at_doit.state.in.us
> >
>
> Tony,
>
> I would have found 'shutdown abort' cleaner than killing PMON.
> You didn't have any recovery to do because it's automatic ... Very briefly
> the
> redo log files contain the delta between memory, where everything happens,
> and
> datafiles, the 'persistent' part of your DB - at least as far as committed
> transactions are concerned. You need to do a recovery when the delta is
> MORE
> than the current redo log files, for instance because you had to restore
> an old
> copy of one of your datafiles, in which case Oracle will ask you to
> provide all
> the redo log files since then. In a 'normal' case, i.e. shutting down
> 'abort',
> killing pmon, unplugging the computer, Oracle is big enough to make sense
> of
> current files. However, when there is a lot of stuff in the current redo
> logs,
> applying them to the datafiles can take some time, which delays the
> availability
> of your database to your users. IMHO, if it was fast in your case it was
> just by
> luck - the synchronisation of memory and datafiles (checkpoint) was not
> too far
> off.
>
> Regards,
>
> Stephane Faroult
> Oriole Corporation
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Stephane Faroult
> INET: sfaroult_at_oriole.com
>
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Received on Wed Jan 17 2001 - 04:23:53 CST