@zacharyreusing That feature only works with internal and thunderbolt hard drives, you can try a app called "keep drive spinning"
@zacharyreusing The hard drive is designed to go into a low RPM state after 10 minutes of inactivity.
@_franksy_ Drives are compatible with Yosemite, we recommend a clean install of the OS. Only known issue is with the custom icon
@23narchy we recommend keeping the drive flat. You want to avoid having the drive in an angle position as this can cause failure