Date: Tue, 4 Feb 1997 21:09:42 +0200 (IST) From: Nadav Eiron <nadav@cs.technion.ac.il> To: Wolfgang Helbig <helbig@BA-Stuttgart.De> Cc: garman@phs.k12.ar.us, hackers@freebsd.org Subject: Re: CMD640b flaw workaround Message-ID: <Pine.GSO.3.95-heb-2.07.970204210307.29771A-100000@csd> In-Reply-To: <199702040835.JAA26420@amadeus.informatik.ba-stuttgart.de>
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On Tue, 4 Feb 1997, Wolfgang Helbig wrote:
> Hi Jason,
>
> Very good! I think your patch for 2.1.5 should also be working for
> 2.1.6.1 so Nadav might give it a try.
> It is working for me for 2 days (and nights) now, with a hd and cd on
> the primary channel and a hd on the secondary. The wd0-disk is my
> root disk containing /etc, /var and swap and the wd2-disk contains
> /usr. Building kernels and "make world" did not crash the system.
> X-Window and Netscape did not crash the system, so I believe it is
> pretty save. Maybe disklabeling does not work, but I cannot test
> that one, since both disks are essential to me.
>
> During testing I experienced, either it works at once and for ever
> or not at all, and luckily it never corrupted any data!
>
> Is there any one else (besides Jason, Nadav and me) with a CMD640b?
>
> Wolfgang
>
I tried installing the patches on my troubled 2.1.5R system, and it
doesn't cure my problem. I think I should describe my problem once again,
as it's not the classical CMD640 bug. I have a machine with a hard disk
(Quantum FireBall) and a CD (Creative x4), both on the primary channel.
The problem is that CD access is unreliable. It's most commonly seen when
I try to serve a CD directly via apache. Under heavy load, some of the
Apace processes will hang while accessing the CD like so:
gatekeeper: {102} ps auxw | grep http | grep D
apache 253 0.0 2.3 660 512 ?? D 8:49PM 0:00.08 /usr/local/apache/ssl.1.3_apache.1.1.1/httpsd -f /usr/local/apache
apache 279 0.0 2.3 672 512 ?? D 8:50PM 0:00.06 /usr/local/apache/ssl.1.3_apache.1.1.1/httpsd -f /usr/local/apache
apache 281 0.0 2.3 672 512 ?? D 8:51PM 0:00.06 /usr/local/apache/ssl.1.3_apache.1.1.1/httpsd -f /usr/local/apache
until after some time the whole machine will hang. I don't have this
problem when running with an ATAPI CD (also from Creative, but a newer
model) on a machine that does not have the CMD640, but it may still be
unrelated. There is nothing to indicate a problem on the console (or dmesg
output). The machine will simply hang, and those Apache processes will
never recover.
As I said before, the patch didn't solve this problem. I asked once on
-questions if anybody had similar experience, and got no replies. Anyone
here knows what's going on?
Thanks for the patch anyhow. I'm sure it will turn out to be useful
someday. When I first installed FreeBSD I spent a month (!) trying to
figure out why it always hangs, until I've heard of the CMD640 problem.
It's comforting to know no new users will have to go through that again.
Nadav
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