For me, a genuine flash external disk has a MaxPower of 2mA, whereas a " real " disk in a USB enclosure has a MaxPower of 200mA . Other than that, I don't know of a way to determine the actual " media " of a linux block device ( bar a vendor / deviceID lookup using the data JSBillings'post retrieves, which is a labourious business ) .-- Talk 17 : 46, 14 January 2011 ( UTC)
