Powering down an USB-powered external hard disk
An USB-powered external hard disk
In Ubuntu, unmounting an USB-powered external hard disk will not work in the same way as the safe removal would in Windows. What it won’t do is powering down the hard drive. You will notice this when you unplug the USB cable, because of the clicking sound coming from the hard disk, similar to the one you would hear if the power supply got suddenly cut off.
I’ve figured out the solution.
First of all, you will need to install sdparm:
sudo apt-get install sdparm
At this point, unmount the drive and then issue the command:
sudo sdparm –command=stop [device]
Replace [device] with whatever you need, and that’s it: your hard disk will spin down and rest, in the same way it would do in Windows after a safe removal. Now you may safely unplug your hard disk.
This is based on my experience with a Western Digital WD Passport/Elements hard disk.
NB: it looks like this won’t work with some Lacie external hard disks.