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Date:      Fri, 26 Nov 2004 13:04:33 +0000
From:      Peter Risdon <>
Subject:   Re: WRITE_DMA failures on 5.3 (but NOT on 4.10)
Message-ID:  <>
In-Reply-To: <>
References:  <000001c4d3af$0dd69240$6500a8c0@jupiter> <>

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Peter Risdon wrote:
> 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].

No - apologies for wasting bandwidth. I got to this stage of research 
very late a couple of nights ago and see I should have stopped a few 
hours earlier. Looking again, this:

hw.ata.atapi_dma: 0

in loader.conf might fix the problem with atapi drives but the

hw.ata.ata_dma: 1

sysctl setting seems to have been the default in 4.10 too, so that can't 
be it.

I think I might try turning off ata dma in a 5.3 system anyway, and 
putting a big drive under load to see what happens, but I fear I'm 
probably back to square one.



the circle squared

network systems and software

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