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motrek Level 1 Level 1 (25 points)

My iMac is about a year old and the internal hard drive makes an annoying high-pitched whine that's pretty normal for older drives.


No problem, I connected an external SSD via USB and boot off of that. It's nice.


The problem is, I can't figure out how to turn off/spin down the internal drive. Here are the things I've tried:


1) You'd think just dragging the drive to the trash can (in the Finder) and thus unmounting it would cause it to spin down. It doesn't.


2) You'd think that enabling "Put hard disks to sleep when possible" in System Preferences would eventually spin the drive down especially because it's unmounted and therefore must be idle, but it doesn't.


3) I did find one way to spin down the drive (after one minute, at least) using the following steps:

          Use Disk Utility to mount the drive and unmount it again

          Use this Terminal command: sudo pmset -a disksleep 1

     Unfortunately I have to repeat these steps every time I boot the computer or wake it from sleep, which is a huge hassle.


Any help with this problem or just information about it is greatly appreciated! Ideally it seems like there must be a magical command line to run or file to edit such that the drive will spin down when unmounted. Crossing my fingers.

iMac, OS X Mountain Lion (10.8.2), 27", 2011
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