[GRLUG] External drive transfer rates

[Bob Kline]

On 10/22/07, Justin Denick <justin.denick at gmail.com> wrote:
>
>
>
> On 10/20/07, Bob Kline <bob.kline at gmail.com> wrote:
> >
> >
> >
> >
> > On 10/20/07, Michael Mol < mikemol at gmail.com> wrote:
> >
> > > On 10/20/07, Bob Kline <bob.kline at gmail.com> wrote:
> > > > On 10/20/07, Bob Kline < bob.kline at gmail.com> wrote:
> > > > > On 10/20/07, Michael Mol < mikemol at gmail.com> wrote:
> > >
> > > [snipped]
> > >
> > > > > > How about:
> > > > > >
> > > > > > mount -t ext3 -o async  /dev/X  /disk2
> > > > >
> > > > >
> > > > >
> > > > > That would seem to make sense, but the
> > > > > man page for mount suggests that the
> > > > > default is async.
> > > > >
> > > > > One can use
> > > > >
> > > > > mount -t ext3  -o defaults /dev/X  /disk2
> > > > >
> > > > > but its unclear why this is useful.  I'm
> > > > > assuming that one doesn't need it, but
> > > > > will try it just to be sure.
> > > > >
> > > > > More later.
> > >
> > > [snipped]
> > >
> > > >
> > > > The async option is apparently the default,
> > > > and has no affect on the slow transfer rates
> > > > I'm seeing.
> > > >
> > > > Some have wondered whether the connection
> > > > is somehow defaulting to a USB 1.1 mode.  But
> > > > if so, I see no way to do anything about that.
> > >
> > > What kind of performance do you get if you try:
> > >
> > > dd if=/dev/X of=/dev/null bs=1M count=1000
> > >
> > >
> >
> >
> > On the Mandriva machine it took 231 seconds,
> > for a bit rate of 4.5 MBps,  or 36 Mbps.  That's
> > about 50% faster than the mounted transfer
> > rate using cp.
> >
> > I'll check the Kubuntu machine after I finish doing
> > something else.
> >
> >     -Bob
> >
>
> Be sure to see what  the DMA specs are too.
>
> hdparm -cuda /devx
>
> As you can see it makes a big differnece
>
> justin at da-boxx ~ $ sudo hdparm -t /dev/hda
>
> /dev/hda:
>  Timing buffered disk reads:  166 MB in  3.02 seconds =  54.92 MB/sec
> justin at da-boxx ~ $ sudo hdparm -d0 /dev/hda
>
> /dev/hda:
>  setting using_dma to 0 (off)
>  using_dma    =  0 (off)
> justin at da-boxx ~ $ sudo hdparm -t /dev/hda
>
> /dev/hda:
>  Timing buffered disk reads:   18 MB in  3.26 seconds =   5.53 MB/sec
> justin at da-boxx ~ $ sudo hdparm -d1 /dev/hda
>
> /dev/hda:
>  setting using_dma to 1 (on)
>  using_dma    =  1 (on)
> justin at da-boxx ~ $ sudo hdparm -t /dev/hda
>
> /dev/hda:
>  Timing buffered disk reads:  166 MB in  3.02 seconds =  54.88 MB/sec
> justin at da-boxx ~ $
>
> It's a kernel option
> CONFIG_IDEDMA_AUTO=y


Thanks.  I'll check this out.

     -Bob
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