USB physical ports

Patrick Hess patrickhess at
Fri Sep 11 10:11:35 UTC 2015

Ernie Luzar wrote:
> How can I confirm 480Mbps transfer rate.

Run "dmesg -a" after plugging in the device. A USB 2.0 flash drive
should be reported with a 40 MB/s transfer rate:

    da1: <Intenso Rainbow Line> Removable Direct Access SCSI-4 device 
    da1: 40.000MB/s transfers

You can verify this by reading from the drive, e.g. by using dd(1):

    # dd if=/dev/da1 of=/dev/zero bs=1M count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes transferred in 52.099073 secs (20609615 bytes/sec)

That's ~20 MB/s, definitely more than USB 1.x could have delivered.


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