External hard drives do not spin down and overheat I have three Newertech Ministack external HDD enclosures attached to my Mac mini Server. The drives inside are continuously overheating, since they do not spin down properly when inactive, while the Ministack's turns off.

Setting is as follows:


Mac Mini - USB2 - Ministack V3 + 2TB HGST Ultrastar
Mac Mini - USB3 - Ministack 2012 + 4TB Seagate Enterprise Capacity
Mac Mini - USB3 - Ministack 2012 + 3TB Seagate Enterprise Capacity


Both Seagate HDDs do not spin down properly.

The strange thing is that they appear to spin down, while the Ministack V3 is still working. But when the Ministack V3 goes into standby, both Seagate Drives start spinning, while the Ministack 2012's fan remains off.

I found out, that when in standby, when SMART is queried, only the drives turn on and later do not spin down.

I had 2 disks dying this summer and try to figure out how to improve the setting.

This is why I have the following programs installed:


iStat
DiskWarrior
Drive Genius
DriveDX + SAT SMART Driver v0.8


In order to eliminate SMART from the equation I turned off HDD monitoring in iStat, eliminated external HDD monitoring in Drive Genius and set DriveDx to 8 hours testing.

Can someone help?
After studying my problem further, I identified the Newertech Ministack 2012 as the cause of my problem. I had to deactivate Drive Genius' DrivePulse, since this program apparently keeps external drives from going into standby. After doing this and switching Newertech USB3 cables for generic USB2 cables, the drives go into standby, but after resuming from standby the fans remain off. This happens in multiple enclosures. It might be a production problem.