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Re: Database Performance Problem between 3:00PM and 4:00PM

From: joel garry <>
Date: Mon, 22 Oct 2007 10:46:39 -0700
Message-ID: <>

On Oct 22, 8:12 am, gazzag <> wrote:
> On 22 Oct, 15:56, wrote:
> > I am Windows 2000 server using Oracle We have strange problem
> > where by database becomes extremely slow between 3:00PM and 4:00PM.
> > Same queries which take 15 seconds before 3:00PM (e.g., 2:55PM) take
> > 3-4 minutes at 3:00PM and after that. Poblem starts right at 3:00PM
> > every day. No of users etc are same. We have asked users not to use
> > the system during that period for isolating performance problem,
> > without any success.
> > When one looks at CPU Usage, Memory Usage and Disk Usage nothing
> > changes between 2:55PM and (3:00PM-4:00PM). I kooked at task mgr, no
> > new processes. I have looked at Windows scheduler, Oracle dbms_job.
> > Nothing is running between 3:00PM-4:00PM. I have no clue why system
> > becomes so slow in that period. I was hoping that some job starts at
> > that time, but cannot find any. Any ideas for troubleshooting will be
> > appreciated.
> The most likely explanation is that something else is running against
> the database between those times. Note: this process need not
> originate from the database server itself, hence nothing in Task
> Manager, Scheduled Tasks and DBA_JOBS.
> Monitor V$SESSION for any suspect sessions.
> -g

I agree, and the first thing I would look for is some performance monitoring tool!

When I was taking networking (circa 1982) in school, my professor was the fellow who had done the arconet, which connected AM/PM minimarts with a 9600 multidrop line. It had just been shutdown due to insufficient performance. Anyhow, he told a story which totally cracked me up. I've posted it before, but can't remember where, so apologies to those who've heard this before. Imagine a thick Hungarian accent...

As I recall the story went, a particular subnet would shut down every night at 9PM. They tried a number of tools (in those days, one wrote ones own), and could only find that some noise started at that time. Finally he went to one of the stores involved and waited until 9, and sure enough it went down. He plugged in a phone (in those days, it was analog), and heard "THIS IS THE VOICE OF GOD!"

Turns out, a large AM transmitter was nearby, and would start broadcasting a Christian radio show at 9PM every night, overwhelming the data signal via induction.

I've also worked in a couple of industrial areas where the place next door would turn on large machines at particular times, affecting hardware that was not isolated enough. Even my current customer recently got affected by some transient packet storm that overwhelmed one of an hp-ux machine's network interfaces, killing telnetd and the console. It's a dirty, dirty world.


-- is bogus.
At least one web page is still up:
Received on Mon Oct 22 2007 - 12:46:39 CDT

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