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Re: Redo Log Size

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Tue, 28 Aug 2001 22:43:23 +0100
Message-ID: <3B8C107B.6BCB@yahoo.com>


Susanne Bagl wrote:
>
> Although I fully agree with you there is still an interesting question for
> me:
>
> Is it better to have larger log members instead of more log groups? Or isn't
> it relevant if there is enough time for archiving before the log-switch
> cycles? Does it matter in case of recovery?
>
> Susanne
>
> "Suzi" <nospam_at_nospam.com> schrieb im Newsbeitrag
> news:fJRi7.22832$6x5.5027620_at_afrodite.telenet-ops.be...
> > 1M .... large ... ??? you mean small !
> > 4 logswitches in less than one minute - why don't you make'm 30MB or
> > something ... should give
> > you a logswitch every 10 minutes or so ... still pretty high but better
> ...
> > We have a 800GB DB with 12 loggroups and each member is 256MB so you
> > shouldn't loose your
> > sleep if you think 2M is too large ... and oh ... as always tune your
> > checkpoints.
> >
> > Who installed your DB - if I were you I would check if I didn't have a
> 100k
> > logbuffer and an 8Mb buffercache ... smells
> > like a default install ...
> >
> > "Bryce Moulton" <brycemoulton_at_eaton.com> wrote in message
> > news:9mgl8q$eek2_at_interserv.etn.com...
> > > I have a 16G db that houses BLOB's anywhere from 0 to 2M.
> > > I have 4 redo log groups with each member being 1M in size.
> > > 1M seems to be pretty large, but I'm getting errors in my alert log
> > because
> > > arch isn't finished archiving when the log group needs to be used again.
> > > Sometimes in the alert log I can see where all 4 of the log groups have
> > been
> > > gone through in less than 1 minute.
> > >
> > > I believe all indications point to increasing size or # of groups, but
> I'm
> > > not sure if Oracle recommends a max size for redo log files.
> > >
> > > Should I increase the size to 2M, or perhaps the # of groups to 5 or 6
> > > groups??
> > >
> > > I would greatly appreciate help. I can't seem to find much documentation
> > on
> > > this.
> > >
> > > Thank you, Bryce Moulton
> > >
> > >
> >
> >

I prefer the best of both worlds. I have "massive" redo logs (where "massive" means they virtually "never" switch by themselves) and then use dbms_job to manually switch them each 'n' minutes (where 'n' is typically 30 or 60).

Then I know exactly when redo switches will be occurring; I know exactly how out of date my standby database will be; I can tweak the dbms_jobs to do it less frequently over night when large stuff is going on etc etc etc

hth
connor

-- 
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."
Received on Tue Aug 28 2001 - 16:43:23 CDT

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