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Date:      Sat, 2 May 1998 20:06:29 -0700 (PDT)
From:      Doug White <dwhite@gdi.uoregon.edu>
To:        Steve Sims <SimsS@IBM.Net>
Cc:        questions@FreeBSD.ORG
Subject:   RE: Monitoring disk access
Message-ID:  <Pine.BSF.3.96.980502200451.21194B-100000@gdi.uoregon.edu>
In-Reply-To: <000001bd7457$5b51b4a0$64468094@Elvis.RatsNest.VaBeach.Va.Us>

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On Thu, 30 Apr 1998, Steve Sims wrote:

> Doug - Do I interpret you correctly:  If APM is enabled in the kernel, it
> explicitly prohibits the drive(s) from spinning down?

I think so, yes.

> If I'm reading you correctly, the Power Management stuff *should* (not to
> infer that somebody ought to make it so) allow the drives to idle down and
> extend the "interrupt timeout" that you mention.

Actually no -- FreeBSD has a cow about it.  Some people (probably
committers) complained about it spinning down and thus stuck the option
in. I think there is an override option that doesn't disable spindown,
you'll have to check the wdc.c code in the kernel.

> A couple of years back, I was playing with one of the first "green machines"
> I'd ever seen (and it did let the drives spin down).  When the disk was hit,
> it would (often) bark about timeouts, but it was innocuous - the FS
> integrity was maintained.  I hacked (mumble, mumble.... wdc-"something")
> that extended the timeouts and it seemed to work pretty good for the few
> days that I was farting around.  IIRC, this was, like, a 1.1.5 system.

I think some computers would take so long to come back that the system
would assume a failure condition and return errors, or worse.

Doug White                              | University of Oregon  
Internet:  dwhite@resnet.uoregon.edu    | Residence Networking Assistant
http://gladstone.uoregon.edu/~dwhite    | Computer Science Major



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