RE: IDS 9.20
Yes it does . . . . Set the way back machine, Sherman.
A long time ago, a certain DBA learned of a great resource to aid his
learning . . . c.d.i. This DBA happened to come across an article
concerning the number of memory segments on an HP box. The DBA noticed that
we would have anywhere from six to ten as listed by ipcs, backed up by
onstat -g seg. The DBA reset SHMVIRTSIZE using the current SHMVIRTSIZE plusthe largest amount of memory added ( (number of segments + 2) * SHMADD),
also including a bit extra. After implementing the change, however small it
was, the DBA then saw a 50-60% performance boost on most Informix reports
and a measurable increase in performance on most OLTP screens. Joy reigned
over a small, but important, change.
The time was about three years ago; the DBA was me.
We are are (still) running an HP K200 box. I'd recommend the same changes
for you:
Find the highest number of SHMADDs that took place over the past
(month).
Add a few more, just to be on the safe side.
Multiply by SHMADD
Add the total memory calculated above to SHMVIRTSIZE
Enjoy the performance.
John Carlson
Informix DBA
EDS - WHSmith USA
3200 Windy Hill Road, Suite 1500 West
Atlanta, GA 30330
> -----Original Message-----
> From: STRONGN [mailto:Neil.Strong@Syntegra.Bt.Co.Uk]
> Sent: Tuesday, August 15, 2000 3:10 AM
> To: informix-list@iiug.org
> Subject: Re: IDS 9.20
>
>
> When you say 4 memory segments, do you mean extents to the
> original shared
> memory segment ( SHMVIRTSIZE / SHMADD )
>
> I ask because we have similar performance problems and
> noticed several ( 10
> ish ) extents being allocated shortly after database startup.
> Obviously, we
> have not sized SHMVIRTSIZE correctly, but does this cause serious
> performance issues?
>
> ( It's also an HP - K class )
>
> Regards
> Neil
>
> "Obnoxio The Clown" <obnoxio@hotmail.com> wrote in message
> news:8n8ddl$8g5$1@news.xmission.com...
> >
> >
> >
> > Was it causing more than 4 memory segments? We're talking
> about an HP here
> > -- a seriously brain damaged memory architecture. :-)
> >
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