I have a new mac mini 2018 with an external raid hard drive connected by Thunderbolt 3 . The drive worked fine on my old IMac 2011 and would sleep when the mac was not in use. On my new mini the drive is always running. If I sleep the mini the drive shuts down for a second then spins up again and continues to run all the time. Is there something I can do to allow the external drive to sleep? I don't want it running all the time and it is getting a bit warm.