I have a freecom external USB HDD, which wont run from a powered hub, so I imagined it was something to do with the powered hub not supplying enough power. However when I connect it directly to a Linux machine, and issue the command:
lsusb -v|egrep "^Bus|MaxPower"
I get the following result:
Bus 002 Device 003: ID 07ab:fc88 Freecom Technologies MaxPower 2mA
(Windows Reports the same thing in fact)
Perhaps that's the power drawn by an internal hub? How can I tell how much power is really being used?