Why USB harddrive is so slow under FreeBSD?

[Erik Trulsson]

On Sun, Apr 12, 2009 at 02:53:42PM -0700, Yuri wrote:
> Dan Nelson wrote:
> >
> > Increase your blocksize.  dd's default is 512 bytes.  Try bs=64k
> >   
> 
> This works, I am getting 25-27 MB/s. Still lower than this device 
> supports (~50MB/s).
> I guess because this VIA controller is very old.

Although the theoretical max speed of USB 2.0 is 60MB/s it is not actually
possible to reach that speed.
In practice the best transfer speed one can get over USB is 35-40 MB/s and
most of the time not even that.

Anything over 30MB/s with USB should be considered quite good, so the
25-27MB/s you are seeing are actually not all that bad.
Some other controller *might* give you a few more MB/s but probably not
more than that.  



-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se