External harddrive case to spin-down drive when idle I try to make external 2.5 hard drives automatically spin down when idle and connected to android devices. The device I have got in mind is a HDMI TV-Stick with USB connector. I tried a few cases/harddrives and found only one old 3.5 case which will spin down the drive when a .nomedia file is present on the drive to prevent indexing. Are there general differences between external drives which can influence their ability to spin down idle drives? Also I would be grateful for hints to android software which can trigger the spin-down and for explanation which requirements to make this work exist in general (for software, disk and case).
It's entirely up to the drive and enclosure. The USB mass storage protocol doesn't have disk-specific instructions, e.g. for spinning up and down drives. The only thing you can do from the Android side is make sure the files aren't in use: e.g. by adding a .nomedia file as you already found.