How to find SCSI device to USB device association.

[Greg KH]

On Mon, May 09, 2011 at 12:12:15PM -0700, StephanT wrote:
> Hi all,
> 
> System description: disk-less ARM, 32M, Linux 2.6.30, 4 USB ports.
> 
> I plug in two USB flash sticks and I get:
> 
> % df -h
> /dev/sda1                 3.7G     32.1M      3.5G   1% /media/sda1
> /dev/sdb1                 7.4G     32.1M      7.0G   0% /media/sdb1
> 
> The sysfs shows:
> 
> % ls /sys/bus/scsi/devices/
> 25:0:0:0  26:0:0:0
> 
> (25 being the sda1 and 26 sdb1)
> 
> % ls /sys/bus/usb/devices/
> 1-0:1.0    1-1        1-1.1      1-1.1:1.0  1-1.4      1-1.4:1.0  1-1:1.0   
>  usb1
> 
> and:
> 
> % ls -l /sys/devices/dw_otg/usb1/1-1
> 
> drwxr-xr-x    4 root     root            0 Jan  1 14:10 1-1.1
> drwxr-xr-x    4 root     root            0 Jan  1 14:18 1-1.4
> ...
> 
> From all this information: how can I find out the association USB 
> device number(1|4) to SCSI device (sda1|sdb1)

Why would you want such a mapping?  It's not stable, changes every time,
and means nothing.

On the other hand, you can do this, look in the sysfs tree for the block
device, it will point you to the usb device from there.

Hope this helps,

greg k-h