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Re: How do I enable UDMA automatically

Kalum Somaratna aka Grendel wrote:
> The strange thins is that I already compiled my kernel (2.2.15) with that
> option set...in fact at the boot up the kernel lists the drives DMA info
> etc..But as the hdparm command shows it doesn't use it for some reason
> unless i manually set it using the "hdparm  -d1 /dev/hda" command....
> Thanks,
> Grendel

I'm glad I could help.

I found this problem exists with my Via MVP4 UDMA66 onboard controllers
and certain drives (Seagate Barracuda and Quantum), whereas Maxtor and
IBM drives work fine.  The problem drives work fine on a Promise
controller in DMA mode, but not on the Via.  It's a shame, too, because
both are faster than the Maxtors for my purposes (web caching).

But in my case...DMA will eventually turn itself off again anyway, even
if you turn it on with hdparm.  If you're using UDMA66 controllers and
drives, you may be seeing the same bug.  So far there is no cure for
it.  As long as you don't put a strain on the drive it won't turn DMA
mode off...but as soon as you push it for a few seconds, it turns off.

Talk to you later.
                    Joe Cooper <joe swelltech com>
                Affordable Web Caching Proxy Appliances

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