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Date:      Fri, 26 Nov 2004 12:46:58 +0000
From:      Peter Risdon <>
Subject:   Re: WRITE_DMA failures on 5.3 (but NOT on 4.10)
Message-ID:  <>
In-Reply-To: <000001c4d3af$0dd69240$6500a8c0@jupiter>
References:  <000001c4d3af$0dd69240$6500a8c0@jupiter>

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craig wrote:
> hi,
> i wrote about this issue some weeks back, but have still not yet adequately
> resolved it.
> (
> 07.html)
> to repeat the original problem, when installing 5.3R it fails about 12% into
> extracting base into \
> on the emergency terminal, there is a stream of warnings and failures
> reading:
> FAILURE : WRITE_DMA status = 51<Ready, DSC, error>... blah  
> this continues until i run out of patience.

This is a really major problem that has affected every 5.3 and the more 
recent 5.2.1 machines I've operated with largish [1] hard drives. The 
novelty of losing several tens of gigs of data any time a drive gets 
busy wears off fairly quickly.

> the advice i received was :

... mainly about checking hardware, and this is _not_ the issue. I've 
googled extensively on this and, as you did, replaced every hardware 
component in the IDE lines, including the disk drives, without affecting 
the problem.

So far as I can make out, there was a change to default settings at some 
point (I haven't scoured the CVS repository to find out exactly when) to 
enable DMA because some newer drives require this[2].

This also affects some attempts to install from CD using CDRW/DVD drives[3].

The only answer seems to be to disable DMA and I hope to put together a 
test machine in the next week to experiment with this. So far as I can 
see, there's a chance that adding:


to /boot/loader.conf might help but I haven't yet tried this.


[1] - at least >80G but I'm not sure where it kicks in.

[2] -

[3] -


the circle squared

network systems and software

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