I'm running 9.10 (Karmic Koala) on a MacBook 4,1 and while I can use the unmount option in file browser to unmount the volumes on the external drive, the HD doesn't spin down as it does in OS X.

Having recently lost a HD, the last thing I want to do is have another borked drive/file system to deal with so don't want to turn the HD off without knowing that it really is safe to do so.

Am I missing some driver support - or is there something I can run through terminal?

I did a search through the forums and Google, and the closest info I could find was here:
http://ubuntuforums.org/showthread.php?t=451344
Though that is for USB HD.