Get attached USB disk to go to sleep?

I have a USB 2.0 disk attached to the USB port of My Cloud. My Cloud goes to sleep per the setting in the administration interace.

The USB 2.0 doesn’t go to sleep at all. Is this normal? Would it be possible to get the firmware to let the USB disk go to sleep until the next safepoint copy or other access?

When the My Cloud “sleeps” it just spins down the internal drive. Power is still provided to the USB port.

My USB disk goes to sleep when connected to a computer, but doesn’t go to sleep when connected to My Cloud. So it is not a question of power being provided to the USB disk, but of access, right?

This probably means that the My Cloud continues accessing or pinging the USB disk and that prevents it from going to sleep.

I was wondering whether a software update could fix this.