Unable to unmount an external usb HDD

Question

In Ubuntu 12.04, when I try to unmount an external USB HDD in Nautilus with the option "safely remove", the HDD is effectively unmounted, but after 10 seconds it is automatically remounted again. This is happened for every USB HDD I have tried.

Answer 1

In case we desperately need to unmount the drive (e.g. to format it) we can do so from the command line:

sudo umount "/media/External USB"

The mountpoint media/External USB will be different on your system and depends on the name you gave to your drive. The mountpoint of your external drive can be seen in the output of the command mount -l.

Answer 2

Unfortunately, this has been a problem for a while. It is safer to use eject instead of safely remove hardware until this is fixed (if ever).