maybe you can give an advice. I have setup a NAS with my cubietruck, works like a charm with a single HDD3.5 sata connected.
I have an usb hub for two HDD 3., this one:
it's a 3.0 usb with external power, it works perfectly on my desktop pc: I can see both the disk, but nothing if connected to cubietruck USB port. It is externally powered up.