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Re: hanging shutdowns

From: Michael Haddon <>
Date: Mon, 27 Feb 2006 18:31:31 -0600
Message-ID: <>


Very well said Edgar,

I completely agree, (along with my earlier post), but wanted to also say that a 'shutdown abort' is not 'SAFE' as I see it.

In a Unix/Linux environment, when you issue a 'shutdown abort' it immediately releases the shared memory segment and semaphores attached to the SGA at the OS level. This is why a shutdown abort is so fast.

This always scares me and I avoid it completely in scripts and scheduled processes. I only issue a 'shutdown abort' if I absolutely had to shut down 'NOW!!', if I could wait, then wait


Edgar Chupit wrote:
Dear Jeremiah,

First of all, I would like to mention that I don't like to shutdown
database without any practical reason (like hardware/OS

And still I would like to argue that under normal circumstances
startup force restrict + shutdown immediate (or shutdown abort,
startup force, shutdown immediate) will run almost as fast and is as
dangerous as a single shutdown immediate.

After shutting down abort in order to perform cold backup you still
need to startup database and close it in consistent mode. Database
startup is not very fast process in it self, because Oracle not only
needs to recover database into consistent state (rollback uncommitted
transactions), but also allocate memory structures and prepare itself
for a normal work. And to shutdown database in consistent state you
still need to issue shutdown immediate.

One of the popular reasons why shutdown immediate can take a longer
time to proceed is because Oracle waits for SNP process to wakeup
(Note: 1018421.102), but this can also happened when the shutdown
immediate is called second time (after startup force), so even
checkpointing and using startup force restrict can cause database to
hang in shutdown immediate mode.

Also, there is a Note: 46001.1 that suggest to minimize usage of
shutdown abort on Windows systems, because it can cause "allocation
problems when Oracle is next started.". Note: 161234.1 that describes
situation when shutdown abort can hang. Note: 222553.1 that states
that startup force can be safer than shutdown abort. And plenty of
other notes that describes different problems that can occur during
database shutdown.

And surely there are many bugs that can occur after shutdown abort
(but under normal circumstances shutdown abort is very safe).

Saying all this, I would like to return to thread subject and suggest
to the original poster to try to convince the management to switch to
hot backups, and forget about shutting down the databases because of
backup at all.

On 2/27/06, Jeremiah Wilton <> wrote:
If you 'alter system checkpoint' before the 'shutdown abort' then it should
be a lot faster for the user with a hanging or prolonged 'shutdown

Jeremiah Wilton
ORA-600 Consulting
Recoveries - Seminars - Hiring

Best regards,
  Edgar Chupit

-- Received on Mon Feb 27 2006 - 18:31:31 CST

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