*BSD News Article 16438


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From: blymn@awadi.com.au (Brett Lymn)
Newsgroups: comp.os.386bsd.bugs
Subject: Re: wd stops on update
Date: 24 May 93 22:07:00
Organization: /usr/blymn/.organization
Lines: 28
Message-ID: <BLYMN.93May24220700@siren.awadi.com.au>
References: <1tafgi$5s7@zaphod.axion.bt.co.uk> <cproto.737791950@marsh>
NNTP-Posting-Host: siren.awadi.com.au
In-reply-to: cproto@cs.curtin.edu.au's message of Wed, 19 May 1993 06:12:30 GMT


lessen@axion.bt.co.uk (Lee Essen) writes:

>>This is a bit of a strange problem!  At completely random times, luckily with
>>a large MTBF, my wd light comes on and stays on and no more disk access is
>>permitted, the processes just block!

>>It appears that the problem occurs when 'update' sync's the drive, when I
>>reboot the filesystems are always clean (thank god!)

>I have the same problem. It seems related to a high rate of context
>switches e.g. running a large make in one xterm and doing some work
>in another xterm often causes the system to lock up as you describe
>it. I.e. processes not using the harddrive work fine (ping, X11, etc)
>but anything going near the disk just locks up.

This bug has been fixed.  I believe that the patches made it into the
latest patchkit.  If not mail me and I will send you a copy of the
patches.  I was bitten by this bug badly and went hunting for it, it
turns out that there are some while loops in the wd drivers that
assume that the drive will come ready eventually, this is not always
the case.  In my situation it looks like if you push the disk too hard
it loses track of whether it is busy or not, by putting a timeout on
the waits for the drive ready and resetting the controller when the
timeouts expire I have eliminated this problem from my system :-)

--
Brett Lymn