Re: Another IDE UDMA issue

Rob Dale (
Sun, 26 Jul 1998 23:32:39 -0400

Jamie Lokier wrote:
> Noting all the discussion about IDE DMA, I thought I'd mention:
> My BIOS enables UDMA, it is configured that way.
> Whenever I run Linux 2.1.x (pre 2.1.111 presumably) with default
> settings, I can expect a complete system freeze within a few days.
> If I explicitly disable DMA with ide0=nodma, I never get a freeze but
> IDE data throughput drops to half its former rate (4.5MB/s vs. 9MB/s
> approx). And there's the CPU load issue. I can't say I've noticed the
> difference in "feel" though. Presumably it's more critical when there's
> lots of paging.
> Recently following an idea on this list, I tried `hdparm -X34 /dev/hda'
> instead of disabling DMA. I think this changes the DMA timings on the
> driver, to something faster (so it's not a cable issue). And now the
> system is reliable again -- I've had no freezes with this setting with
> several weeks use. The throughput is back to the UDMA rate.
> I'm under the impression that this is a timing thing that the kernel
> can't possibly work out reliably. But I thought I'd mention that I do
> have UDMA problems that can be cured without turning off UDMA.
> I have one of the supposedly "good at UDMA" Quantum drives -- a Quantum
> Fireball ST 6.4GB.
> My chipset is a VIA VP2/97.
> In not setting the drive right, the BIOS is presumably one that sucks. :-)

I have the same chipset with a cheap Seagate 3.2GB. No problems.
I also have the MVP3 with a Maxtor 7GB with no problems.
I'm about to do some speed tests now ;)

BTW, what mobo is it you have with VP2/97? Mine is
the FIC PA-2007.

Robert Dale

"arrest this man he talks in maths" RADIOHEAD OK COMPUTER

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