Re: Log Buffer

Hey all,

    I just wanted to say thanks to everyone who is discussing this with me, I am enjoying it. Anyway, I am assuming that the problem has to be disk contention. As I said earlier, I only have two hd's on one controller. I am going to try and increase the buffer a little bit and increase the redo logs themselves as well. Maybe sooner or later I'll get this thing uder control. Since we do not use RMAN I don't really need my redo logs going to town every 10 minutes, I would like to get it down to to about every half hour or so. What do you boys think of that? Kev
----- Original Message -----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Sent: Friday, March 23, 2001 5:30 PM

> Hey Kevin,
>
> My Oracle Perf Tuning instructor suggested doubling the LOG_BUFFER until
the
> requests get under control. Problem is that each bump requires a reboot.
> Since ours was severe enough, I went from 1MB to 4MB. When that wasn't
> enough, I went to 12MB. This is over the course of almost 12 months, due
to
> uptime requirements.
>
> This is fine unless your rego log files are in contention with other
> datafiles (archives, datafiles, controlfiles) in the database. A larger
> LOG_BUFFER may help, but it's just a workaround for the underlying
problem.
>
> For now, our whole shmear is on an HP AutoRaid. I know, I know. It
seemed
> like a good idea at the time (before Oracle training). I'm seeing LGWR
> write times up to over a second at peak. Not only that, but even with a
> LOG_BUFFER of 12MB in a 500MB total SGA w/175 users, I'm getting almost
3000
> redo space requests per week. Ouch.
>
> Oh, to be able to use Loney's 15-drive setup. Hell, I'm not asking for
22!
>
> BTW, I'm on 8.0.5.2.0 on HP/UX 10.20. Next week is HP/UX 11.0, with 8.1.7
> and an extra RAID0 for my redos to follow. Yay!
>
> Good luck!
> Rich Jesse System/Database Administrator
> Rich.Jesse_at_qtiworld.com Quad/Tech International, Sussex, WI
USA
>
> > -----Original Message-----
> > From: Kevin Kostyszyn [mailto:kevin_at_dulcian.com]
> > Sent: Friday, March 23, 2001 14:06
> > To: Multiple recipients of list ORACLE-L
> > Subject: RE: Log Buffer
> >
> >
> > yes, I think that does help. I am thinking I am going to
> > make them larger?
> > 21 requests
> >
> > -----Original Message-----
> > Sent: Friday, March 23, 2001 2:46 PM
> > To: 'Kevin Kostyszyn '
> >
> >
> > Hi...
> >
> > I don't think so...
> >
> > you must adjust your LOG_BUFFER acoording to:
> >
> > select substr(name,1,25) Name,
> > substr(value,1,15) "VALUE (Near 0?)"
> > from v$sysstat
> > where name = 'redo log space requests';
> >
> > Hope this help!
> >
> > -----Original Message-----
> > To: Multiple recipients of list ORACLE-L
> > Sent: 3/23/01 8:35 AM
> >
> > Hello DBA's
> > You know, I read somewhere that you can make your log_buffer 10
> > percent of
> > your total sga. So if you had a 500mb sga you could have a 50 mb
> > log_buffer? What do you guys think, the illustrious Ross doesn't like
> > such
> > large log_buffers.
> >
> > Sincerely,
> > Kevin Kostyszyn
> > DBA
> > Dulcian, Inc
> > www.dulcian.com
> > kevin_at_dulcian.com
>
>
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> Author: Jesse, Rich
> INET: Rich.Jesse_at_qtiworld.com
>
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-- 
Author: Kevin Kostyszyn
  INET: kevin_at_dulcian.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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