Hello deBabba,
I tested Unraid with a WD My Passwort Ultra USB-Hdd. I thing the WD Hdds are a peace of s**t.
Now running with Seagate and spin down works as expected.
My Cash drive does not spin down. Might be influenced on the dockers running on the M2. Checking this is a task for future-me.
For now, this setup (USB HDD, no parity, non-ecc ram) is what covers my current requirements. And a license was worth the money.
(And yes, setup is not recommended and not supported…)