[kwlug-disc] USB 2.0 vs. 3.0 on Linux

[B.S.]

On Mon, 22 Sep 2014 20:16:06 -0400
Khalid Baheyeldin <kb at 2bits.com> wrote:

> On Mon, Sep 22, 2014 at 7:59 PM, William Park <opengeometry at yahoo.ca>
> wrote:
> 
> > - What kind of test?
> >
> 
> Copying around 100GB worth of files, most of them multi-gigabyte in
> size, from one disk to the other. Using rsync, while the files do not
> exist on the target


It would be interesting to know what the USB to internal HD speed is /
only - i.e. not usb3 to usb3. The numbers would go up? Or CPU load
level down? (Given Lori's note that speed is appropriate for given
disk, presumably the numbers wouldn't change much?)

'course if we want to be depressed, another interesting number would be
internal HD to USB (write) speed.

Khalid, for your USB2 tests, was that also USB2 to USB2, or was it USB
to internal HD? I read it as to internal HD - now I'm not sure if that
was your intent.

I'll guess Ext3?


On Mon, 22 Sep 2014 18:49:36 -0400
Khalid Baheyeldin <kb at 2bits.com> wrote:

> So, I got two USB disks that support USB 3.0 speeds, and ran some
> times.
> 
> On an older machine that has only USB 2.0 ports, the speeds is as
> follows: 18.9 MB/s to 19.6 MB/s.
> 
> On a machine that has USB 3.0 ports, with both disks connected to the
> blue ports, and Ubuntu Server 12.04, the speed was only 59 MB/s.
> 
> From what I read, real tests on USB 3.0 (ignoring the nominal speeds)
> should be 10X as fast as USB 2.0, which should be 200 MB/s at least.
> 
> So, is it because these are portable disks and the spindle is 5400
> RPM? Or is it a bottleneck somewhere else?