Re: disk corruptions on "tuned" disks Was: APM killing low-latency

Dan Hollis (goemon@sasami.anime.net)
Wed, 10 Nov 1999 18:00:30 -0800 (PST)


On Thu, 11 Nov 1999, Benno Senoner wrote:
> On Thu, 11 Nov 1999, Dan Hollis wrote:
> > On Thu, 11 Nov 1999, Benno Senoner wrote:
> > > It would be nice if we could collect some data about problematic
> > > drives / mainboards.
> > > Alan any know drives ?
> > > ( If I get some data I will write a little tool which automates this)
> > VIA VP3/MVP3/MVP4 chipets.
> thanks, but what is the exact problem source , DMA or unmask IRQ ?

DMA

> > Put any CDROM/DVD in DMA mode and it will work
> > for a while and then eventually lock the PC up. This is a hardware flaw.
> Doh ! really bad news :-(
> What about watching DVDs ?
> I'm watching DVDs on windoze using a software-only player,
> and without DMA you get nast frameskips ,because the PIO
> transfer uses too much CPU.
> I'm watching DVDs for hours ( DMA enabled) without any lockups.

It may be ultra dma only bug. Im not sure. My DVDROM and CDROM both
support udma.

> But are you sure that every ATAPI CDROM drive on the planet
> has this hardware flaw.

Its the controller not the CDROM at fault

> I stressed my CDROM drives quite a bit, and was unable to lock up the box.

What controller and what drives

> > There is no known software workaround. This is not the ISA DMA bug either.
> > This is a completely different bug.
> Interesting, any pointers for more accurate infos on this topics ?

All the articles on this have long since expired from altavista :-)

> How is this handled my other OSes ?

They dont run DMA.

> > Promise Ultra66. No DMA on CDROM/DVDs. It just wont work. At all.
> PS: why should recent ATAPI CDROM let you set the DMA mode, when they
> know that it could lead to problems ?

Its the controller not the CDROM at fault

-Dan

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