I want to spin down external hard drive from the terminal before unmounting.
It is an sata drive connected through usb.
Running hdparm gives this
ry@G62x:/media$ hdparm -S10 937b2299-48ff-4a9c-8228-67ed4453e8fb/
937b2299-48ff-4a9c-8228-67ed4453e8fb/:
setting standby to 10 (50 seconds)
HDIO_DRIVE_CMD(setidle) failed: Inappropriate ioctl for device