Property me an extra power-saving 2.5-inch HDD from Verbatim buy, which corresponds to the USB specifications (5 volts at Unfortunately, my Fritz box with the HD problem. Remedy has this USB Hub geschaft with active power supply. While the power supply is sufficient not for 4 units, each with 500mA, but 2 disks can operate. Processing continues in order. The device works error-free at a Fritz box. On Windows, Linux, etc. I not yet tested it.