我有这个外部 USB 磁盘：
kaefert@blechmobil:~$ lsusb -s 2:3
Bus 002 Device 003: ID 0bc2:3320 Seagate RSS LLC
从这个 dmesg 输出中可以看出，有一些问题阻止了该磁盘被挂载：
kaefert@blechmobil:~$ dmesg
...
[ 113.084079] usb 2-1: new high-speed USB device number 3 using ehci_hcd
[ 113.217783] usb 2-1: New USB device found, idVendor=0bc2, idProduct=3320
[ 113.217787] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 113.217790] usb 2-1: Product: Expansion Desk
[ 113.217792] usb 2-1: Manufacturer: Seagate
[ 113.217794] usb 2-1: SerialNumber: NA4J4N6K
[ 113.435404] usbcore: registered new interface …