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RE: control file parallel write

From: Rahul <rahul_at_ratelindo.co.id>
Date: Mon, 7 Aug 2000 12:09:28 +0700
Message-Id: <10581.113939@fatcity.com>


if these processes use the "rdbms icp msg" event to record waits/timeouts then why the event "cntrl file prallel write" waits increase ??

> ----------
> From: yong huang[SMTP:yong321_at_yahoo.com]
> Reply To: ORACLE-L_at_fatcity.com
> Sent: Monday, August 07, 2000 12:44 PM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: control file parallel write
>
> Thank you, Steve. I should've checked your Web site before I posted.
>
> Indeed I find the same description at Metalink (as in Bug report 723987
> although it's not a bug). It says this heartbeat makes sure the instance has an
> exclusive lock on the thread. I think it's useful only in OPS. It's kind of a
> waste of CPU for a single instance database.
>
> Oracle documentation says LGWR, DBWR, LCK0 use the rdbms ipc message event to
> indicate they're idle. Why does it not say CKPT? Maybe the documentation has
> not been updated. By the way, does LGWR, DBWR or LCK0 modify the control file
> when they time out?
>
> Best regards,
>
> Yong Huang
> yong321_at_yahoo.com
>
> --- Steve Adams <steve.adams_at_ixora.com.au> wrote:
> > Hi Yong,
> >
> > In answer to a similar question, available in the question and answer
> > section of my web site for 3 March 2000 I wrote, "In 8.0.5 a heartbeat
> > mechanism was included in CKPT's timeout action (every 3 seconds) to
> > update the checkpoint progress record for the thread in the
> > controlfile." However, the timeout being referred to here is the routine
> > timeout of its 'rdbms ipc message' wait every 3 seconds, NOT the
> > instance checkpoint timeout that is controlled by the
> > log_checkpoint_timeout parameter. If you were to change that parameter
> > to 2 you would notice a lot more than increased 'control file parallel
> > write' waits. You would also notice very bad performance!
> >
> > Regards,
> > Steve Adams
> > http://www.ixora.com.au/
> > http://www.oreilly.com/catalog/orinternals/
> > http://www.christianity.net.au/
> >
> >
> > -----Original Message-----
> > From: yong huang [mailto:yong321_at_yahoo.com]
> > Sent: Monday, 7 August 2000 8:34
> > To: Multiple recipients of list ORACLE-L
> > Subject: Re: cntrl file paralel write
> >
> >
> > Rahul,
> >
> > The same happens to my database. It seems the CKPT process is touching
> > the
> > control file every 3 seconds, presumably because the LGWR does its job
> > every 3
> > seconds. If you change log_checkpoint_timeout to 2, you'll notice your
> > control
> > file parallel write waits for redo log writing every 2 seconds.
> >
> > Yong Huang
> > yong321_at_yahoo.com
> >
> > you wrote:
> >
> > List,
> > a new instance, just one user connected (SYS),
> > select * from v$system_event shows that the
> > "control file parallel write" are increasing....!!
> > "total waits" are increasing by 10 per 30 seconds...
> > whenever i query the v$system_event i see an
> > increase in the time_waited,waits in this event..
> >
> > is this the one to ignore ?
> >
> > 8.1.5, AIX
> >
> > Rahul
>
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> --
> Author: yong huang
> INET: yong321_at_yahoo.com
>
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Received on Mon Aug 07 2000 - 00:09:28 CDT

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