A more complete log about my disk access errors

[Kerry Hoath]

You may also find that certain drives want to go into udma66
which makes sense since that is their fastest powerup dma mode. Now if you don't happen
to have a UDMA66 cable, then you can experience dma timeouts or crc errors,
because Linux thinks the drive is in superfast mode, the drive does too but the signals on the cable
are getting corrupted due to the lack of conductors in the cable.
UDMA 66 has 80 conducters and normal ide has 40, although both only have 40 pins.

I found that with my Quantum 30gig drive, I couldn't enable dma reliably
unless I had an UDMA66 cable on the Via 82c586 controller. Some new
drives suck in pio mode providing a lack lustre 5 megabytes per second
but run at 15 megabytes when udma is enabled.
If anyone wants any more information on Linux and DMA/UDMA let me know under Linux,
sadly under Windows you'll have to ask Kirk Wood about the dark side :-)

Regards, Kerry.
On Sat, Jun 02, 2001 at 04:53:14PM -0500, Kirk Wood wrote:
> First, understand why Windows 2000 doesn't complain about the DMA. If the
> drive times out twice (ever) then it no longer uses DMA ever. So it won't
> complain. It won't tell you. In fact, win winclows 98 they burried any
> indication that this had happened. It happens more often them many people
> realize.
> 
> Having said that, if you didn't have DMA support compiled into the kernel
> you wouldn't get the errors. Yes, it must be compiled in if it is to be
> used. (DMA falls back to PIO in case of failure and PIO always remains
> available.)
> 
> As for fixing this, it is either the motherboard or the drive. I know that
> doesn't help. You might check to see that DMA is turned on in the
> BIOS. (Linux will try anyway, winblows just acts like it is using DMA and
> doesn't really.) Otherwise try another DMA drive and see if the problem
> resolves.
> 
> =======
> Kirk Wood
> Cpt.Kirk at 1tree.net
> 
> Nothing is hard if you know the answer or are used to doing it.
> 
> 
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Kerry Hoath: kerry at gotss.net
alternatives: kerry at gotss.eu.org or kerry at gotss.spice.net.au
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