[ggm]

An externally connected USB-Sata device providing disk(s) with external power management, through a single USB port? sure.

What I had was a 4 device SATA hat, 2 USB ports bridged on each half of the divide to form the channel for data, GPIO pins were used solely for card control and power distribution. It was clever, but not sensible.

People who construct RAID sets over USB attached devices on discrete ports also wind up in odd places. The device enumeration can be semi random and so you have some logistical barriers to things (ZFS amongst other sane things, writes the ZVOL/DEV information into the structure on disk so which enumerated device it is becomes less important) as well as a power distribution problem. I ran an early version of this using an unpowered USB hub with 4 USB sticks and it was very badly behaved.

When I do my 3-2-1 the removable external ZFS drive is USB-3 connected.