Re: [Thinkpad] X40 HD/USB very slow?

From what I understand, this is about an external USB drive, which would
only use DMA between the drive and the USB/IDE chip, and the setting of
whether to use it or not is not exported to the computer.

On Nov 14, 2007 8:56 AM, RWM <RWM@rwmann.com> wrote:

> How about checking Device Mangler to see if the X20 HD ATA Controller
> has inadvertently been set to (or defaulted to) a slow speed, such as
> PIO Mode 0 (3.3) versus DMA-2 (16.7) or UDMA-6 (133).
>
>
>
> Scott Matthews wrote:
>
> >It's a Samsung drive in an Antec enclosure -- and it's perfectly fast on
> the
> >X61s.
> >
> >I think he was saying that his drive was only serving at 3.5MB/s -- and
> so
> >even though he had a potential of ~20MB/s vis USB2, it was limited to
> >3.5MB/s because of his drive.
> >
> >I'm not quite sure what to check, but it's definitely *much* slower on
> the
> >X20 than the X61s...
> >
> >Thanks, -Scott
> >
> >
> >
> >
> >>I remember reading here that the T40 had an early and buggy
> implementation
> >>of USB 2.0, so it wouldn't surprise me if the X40 had the same.
> >>
> >>However, 3.5MiB/sec is much faster than USB1. USB 2.0 has a theoretical
> >>
> >>
> >peak
> >
> >
> >>speed of 55MiB/sec, but the command overhead in the USB stack and
> storage
> >>protocol makes it really closer to 20MiB/sec. Divide that by 40 (the
> speed
> >>multiplier from USB1/USB2) and you get 500KiB/sec.
> >>
> >>What model of USB drive is it? I'm wondering what the bandwidth of the
> >>USB/IDE chip used is.
> >>
> >>On Nov 14, 2007 7:43 AM, Scott Matthews <scott@turnstyle.com> wrote:
> >>
> >>
> >>
> >>>Hi all, I just plugged a fast USB2 drive into my X40. I've used the
> same
> >>>drive on an X61s, and it was perfectly fast. But on the X40, it's very
> >>>slow.
> >>>
> >>>A bit of Googling (http://forum.thinkpads.com/viewtopic.php?t=27910)
> and
> >>>
> >>>
> >I
> >
> >
> >>>found somebody with the same problem, and he decided that the
> bottleneck
> >>>was
> >>>his X40 drive -- at about 3.5MB/s (not much faster than USB1) as
> opposed
> >>>to
> >>>about 25MB/s for USB2.
> >>>
> >>>Does anybody know if the X40 drive simply can't transfer data at a
> >>>reasonable speed?
> >>>
>
> --
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