Since when is "udisksctl power-off -b /dev/sdX" only for drives connected through USB?!?!
> Error powering off drive: No usb device (udisks-error-quark, 0)
The man pages also don't mention this and instead say:
> The exact steps for powering off the drive depends on the drive itself and the interconnect used. For drives connected through USB, the effect is that
WTF?!?