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SubjectRe: UDMA
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In message <34989116.7029EF31@pobox.com>, mlord writes:
> The 32-bit IO and multcount work only for PIO, not DMA.
> On some drives (?), multcount might even slow down DMA,
> though there is no evidence to support this theory.
> Neither of these buys anything when DMA is used.

Ok, I just went on the hdparm man page which doesn't really say much about
when certain settings should be used. I just turned on everything the
man page indicated would increase performance and none of it ever caused
any problems. I turned off multcount and 32 bit I/O since I am using
DMA mode 2 on my non UDMA drives. Thanks for the further information.

> The write-caching can be turned on ("hdparm -W1") to speed up writing,
> but one must be careful to turn it off again at system shutdown,
> to ensure the cache is flushed before reset or poweroff.

If turn off UDMA in the bios for this drive, I am able to use write
caching without a hitch. If I enable UDMA for this drive in the bios,
write caching still causes irq timeouts. I do turn it off at shutdown
as I saw advice to do so earlier on the list. Perhaps the hdparm man
page should say something about this?

> Mmm.. not sure what the issue might be.
> See if things are any different with 2.1.73, when it appears.

Deal. I'll keep write caching off for now and let you know how it goes
when 2.1.73 comes out.

Thanks,
Roy

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