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Date:      Thu, 23 Apr 1998 10:19:05 -0400
From:      "Steve Sims" <SimsS@IBM.Net>
To:        <questions@FreeBSD.ORG>
Subject:   Monitoring disk access
Message-ID:  <000001bd6ec2$c6b36bc0$64468094@Elvis.RatsNest.VaBeach.Va.Us>
In-Reply-To: <>

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Does anyone know how (or even if there's a way) to monitor which processes
are actively engaged in reading or writing to a disk?

The reason I'm asking is, I've put together a (headless) box that does a
very limited amount of work - 22 hours out of the day it's doing *nothing*,
but cron wakes up a few times a day to do some trivial work and mails the
result to a local recipient.

I'm sure that it's not hitting swap, since I've disabled 'swapon' in the
startup files.  (The machine has more than enough RAM to run the periodic
processes, anyway.)

I've also done the obvious by moving kern.update way out to 3600, so sync's
should (in theory) only happen once an hour.

But the problem remains that the disk doesn't ever spin down, even though
all the APM stuff is enabled and the disk is set to spin down after 60
seconds of inactivity.

The box is a "green" 486/66 with 40Mb and a power-management aware WD IDE
drive and virtually nothing else, hardware-wise (OK, a modem).

// Flame Bait:
Under DOS, or Win'95, the box does just what I'd expect - if you leave it
alone for a minute or two it goes to sleep; shuts down the monitor, disks,
// end of flame bait

As a test, if I boot it up in single-user the box does what is expected:  it
politely shuts off the drives and waits silently for "something to happen".

I've got to believe that something is periodically touching the disk and
that's enough to reset the sleep-mode timer.  Is there a way of checking to
see what's prodding the hard drive?

Ideally, the box should realize that nothing's going on and go to
snooze-mode.  It doesn't.

Surely some of you laptop-folks have solved (or, at least, seen) this - Do
your hard-drives ever shut down if you go get a beverage and a snack?

Any ideas?


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