Why USB harddrive is so slow under FreeBSD?

[Tim Judd]

On Sun, Apr 12, 2009 at 1:54 PM, Yuri <yuri at rawbw.com> wrote:

> I have FreeBSD-71 running with USB controller:
> uhci0: <VIA 83C572 USB controller> port 0xa800-0xa81f irq 21 at device 16.0
> on pci0
>
> I connected to it Toshiba USB hard drive HDDR500E03X:
> umass0: <Toshiba External USB HDD, class 0/0, rev 2.00/1.03, addr 2> on
> uhub4
> da0: <Toshiba External USB HDD 1.03> Fixed Direct Access SCSI-4 device
>
> When I try to copy data with 'dd if=/dev/da0s1 of=/dev/null count=10000' it
> only achieves has 0.65MB/s transfer speed.
>
> What's wrong, why is it so slow?
>
> Yuri
>


uhci is 1.0 devices specs of 12Mbit/sec
ohci is 1.1 devices
ehci is 2.0 devices specs of 480Mbit/sec


Seeing various PCs boot and during the probe, typically I see 1 ehci, and
multiple uhci and ohci devices.


Your Toshiba External USB HDD must have 2.0 speeds to be able to transfer at
that speed... hooking a 2.0 device into a 1.x port will either cause port
shutdown, or a backwards compatible downstep for the device in terms of
speed.


Hope this explanation helps.

--TJ