I am using LaCie Brick Mobile. It is connected to my Mac using 6 pin firewire cable. But the external HD refuses to spin-down. This hard drive is very quiet. But if I place my hand on top of the drive, I can feel a slight vibration caused by the spinning HD. There is no on/off button in this external HD. I would like to let it spin down after a period of inactivity to prolong its life. Can anyone suggest a way to do that?