Quote Originally Posted by Styno
Have you tried the AMSET utility as well?
To be honest, I didn't. Now I did, and it doesn't work

And this tool: http://support.wdc.com/download/index.asp?swid=17
I also found this in the knowledge base:
USB mass storage devices are seen as SCSI devices under Linux.
Accoustic management doesnt power down the drive. All it does is slow down seek movements a bit, so your drive doesn't make as much noise. I can set the accoustic management with the Hitatchi feature tool already..

I know that an USB mass storage device is seen as a SCSI device. Still, SCSI devices can be powered down as well..