External USB HDD is not spinning down

[kriticar]

@cocomic

For anybody else having trouble with usb hard disks not spinning down (or spinning up shortly after having spun down), it all might be caused by SMART trying to read stats from the disk every x minutes.

To fix it, make a copy of /usr/lib/udisks/udisks-helper-ata-smart-collect (rename it to .orig or something) and then create a new file with the same name, where you type

#!/bin/sh 
exit 0

chmod 755 and you should be fine (at least it worked on my WD Mybook).

I can confirm that your solution works for WD Green 4TB.
Thanks a lot.

Regards.