I have a set of external disks I use for backup purposes for my Plex box. In their next to second final state, where I setup something to turn them on and off with a script, I have them wired to a xbox 360 power supply and a 10 port powered usb hub. The hard drives connect to the hub, the hub to the server. As you do. The fun part, the hub isolates power to the devices from the host pc so I can simply turn off power to the hub and the usb things disconnect. The idea being, if the usb controllers in the drives don’t have power from the hub or pc, it’s as if they’re physically disconnected so I can get around any stability issues they may have.