USB physical ports

Patrick Hess patrickhess at
Fri Sep 11 13:48:32 UTC 2015

William A. Mahaffey III wrote:
> On 09/11/15 07:10, Ernie Luzar wrote:
> > But the real question is why is Freebsd USB rates capped at 20Mbps 
> > when the hardware says it's capable of 480Mbps?
> I think you are confusing bits & bytes. 480 Mbps = 60 MBps, lower case 
> 'b' is bits, upper case 'B' is bytes, 8b / B (8b per B).

That's the first reason.

In addition, just because the bus is capable of transmitting up
to 480 Mb/s, that doesn't mean the devices connected to that bus
will also be able to process data at that rate. As a matter of fact,
most el-cheapo USB thumb drives won't. Try that again with a modern
HDD or even an SSD and you'll get much better results.


More information about the freebsd-questions mailing list