Blog by an Apple Certified Tech


How to unmount external/eject drives?

Sometimes we get a disk or disk image stuck and not gets eject even after restarting the Mac holding down the mouse button. If that does not unmounts, you can force it with a Terminal command. In order to do thid, launch Terminal and use “df” to list the drives.
Search and locate the drive that you want to unmount, such as /dev/disk3al.
Then run command “diskutil unmountDisk force /dev/disk3al″ this should force it to unmount.

Make sure you try this command after making sure that you have pointed the correct drive.