[GRLUG] External drive transfer rates

[Justin Denick]

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


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