I have an external drive connected to a 13Inch 2012 MBP I use as a HTPC. Even though I have deactivated "put hard drives to sleep" in power management it will spin down after a while anyway. I have tried the application Keep Drive Spinning, it looked like it was working but the drive spun down anyway. I have tried the terminal command sudo pmset -c spindown 0 and caffeinate. The drive still goes to sleep using theese commands. I use 10.12.5, macOS sierra. Any ideas on how to prevent an external USB drive to stop spinning down? I have googled but havent found anything that works in sierra apparently.