Re: Life after NSLU2?

--- In nslu2-general%40yahoogroups.com">nslu2-generalyahoogroups.com, "Paul Bonsor&quot; <pb89552...> wrote:
&gt;
> I can thoroughly recommend the Synology DS107, and I'd all there other
&gt; products are the same.
&gt;
> Paul B
>
> On Sat, Mar 29, 2008 at 4:32 AM, Carl Lowenstein <clowenstein...>
> wrote:
&gt;
> > On 3/28/08, Carl Zetie <carl.zetie... <carl.zetie%40gmail.com>>
> > wrote:
&gt; > >
>; > > docbillnet:
> > > >Why not buy another NSLU2?
&gt; > > Because the file transfer speed is just too slow. It's OK for
overnight
>; > > backups where throughput really doesn't matter, and as a learning
> > platform
> > > for Linux, but as a file server it just doesn't cut it. When the USB
> > > interface runs at (theoretically) 480Mbps and the network
interface is
> > > capable of 100Mbps (and I'm thinking of upgrading to gigabit
Ethernet),
> > file
>; > > transfer speeds that top out at just a handful of Mbps is pretty
&gt; > > disappointing.
> >
>; > By the way, one should be careful about megabits and megabytes. The
> > USB interface is 480 megabits per second, which is 60 megabytes per
> > second. The ethernet at 100 megabits per second actually tops out at
> > about 10 megabytes per second.
> >
>; > Achieved data transfer rates using dd(1) between two USB disks seem to
> > top out at 10 megabytes per second. Every byte is handled twice by
> > the CPU, once for reading and once for writing.. If one uses rsync,
&gt; > the extra checksum calculations saturate the slow CPU in the NSLU2 and
> > the disk to disk rate drops to 3 megabytes per second.
> >
>; > So yes, it isn't the worlds fastest CPU and asking it to do all this
>; > extra stuff makes the over-all transfer rate pretty slow.
&gt; >
>; > But remeber that a handful of megabytes is eight hands full of
megabits.
> >
>; > carl
>; > --
> > carl lowenstein
> > marine physical lab, u.c. san diego
&gt; > clowenstein... <clowenstein%40ucsd.edu>
> >
> >
>;
>
> [Non-text portions of this message have been removed]
>
Hi,

> Achieved data transfer rates using dd(1) between two USB disks seem to
> top out at 10 megabytes per second. Every byte is handled twice by
> the CPU, once for reading and once for writing.. If one uses rsync,
&gt; the extra checksum calculations saturate the slow CPU in the NSLU2 and
> the disk to disk rate drops to 3 megabytes per second.
>

I posted my test results about this yesterday. But, I am running rsync
between the two USB drives with --size-only specified, therefore there
should be very little extra work for rsync to do, apart from copying
the files. Still, my CPU is pegged at 100% and the xfer rate goes down
to the approx. 3MByte/Sec seen.

I wonder why?

Cheers Brian

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