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Re: Log file synch / direct path writes

From: Ramon E. Estevez <com.banilejas_at_codetel.net.do>
Date: Mon, 24 Jun 2002 12:18:27 -0800
Message-ID: <F001.00485AF4.20020624121827@fatcity.com>


Dennis,

100MB archive log size.

Ramon

> Ramon, along the lines of Beth's idea here, how large are the archive logs
> you are producing?
>
> Dennis Williams
> DBA
> Lifetouch, Inc.
> dwilliams_at_lifetouch.com
>
>
> -----Original Message-----
> Sent: Monday, June 24, 2002 1:19 PM
> To: Multiple recipients of list ORACLE-L
>
>
>
> Ramon,
>
> For one thing, LGWR will write the log buffer when it is 1/3 full, or if
> it reaches 1MB. So, its useless to have the log buffer more than 3MB.
> The space beyond 3MB could never possibly be used.
>
> My .02
>
> Beth
>
> -----Original Message-----
> Sent: Monday, June 24, 2002 1:28 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Jared,
>
> Just to clear my thoughts, doubts and keep learning from the list.
>
> What implications can cause having a big log buffer.
>
> As I can remember, LGWR copy data from the log buffer to the redo logs
> when
> log buffer is 1/3 full, timeout, commit and a few more.
>
> So it will fire when the first one occurs, base on that theory, what
> matters
> if the log buffer is 1mb, 10mb, 100mb. Anyway LGWR will copy the data
> to
> the redo logs.
>
> I had some problems of performance the last week and some of you got
> surprised because I had a log buffer of 100MB.
>
> I have never read some documentation, obviously have to read more and I
> am
> doing it believe me, that tells not to do it.
>
> I would like some comentaries or your considerations about this,
>
> TIA
>
> Ramon
>
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Saturday, June 22, 2002 1:33 PM
>
>
> >
> > Just how large is your overly large log buffer?
> >
> > 10 meg?
> >
> > 100 meg?
> >
> > 1 Gig??? ( ok, I've never heard of one this big,
> > but you never know ;)
> >
> > Jared
> >
> > On Friday 21 June 2002 12:48, Erik Williams wrote:
> > > I have an instance that is waiting on log file synchs. I suspect
> that
> the
> > > waits are a result of a overly large redo log buffer. There are also
> > > considerable waits on direct path writes. The redo logs are on
> QuickIO,
> so
> > > I assume that the writes LGWR is writing asynchronously and not a
> source
> of
> > > the log file synchs. I want to be sure that the log file synchs and
> direct
> > > path writes are not related before I begin to experiment with the
> size
> of
> > > the redo log buffer. How can I be sure that the waits are being
> caused
> by
> > > DBWR and not LGWR? What are possible fixes for the direct path
> writes if
> it
> > > is the DBWR causing them? Multiple DBWR? The datafiles are not on
> QuickIO,
> > > just the redo.
> > >
> > > Thanks
> > > Erik
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Jared Still
> > INET: jkstill_at_cybcon.com
> >
> > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> > San Diego, California -- Public Internet access / Mailing Lists
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Ramon E. Estevez
> INET: com.banilejas_at_codetel.net.do
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Seefelt, Beth
> INET: Beth.Seefelt_at_TetleyUSA.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: DENNIS WILLIAMS
> INET: DWILLIAMS_at_LIFETOUCH.COM
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Ramon E. Estevez
  INET: com.banilejas_at_codetel.net.do

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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Received on Mon Jun 24 2002 - 15:18:27 CDT

Original text of this message

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