How to safely remove a USB external drive?
To safely remove i.e. disconnect an external USB drive you need to manually unmount all of its partitions (represented by 'drive icons'):
either in Unity Launcher
or in Nautilus
In the example above: to remove my Hitachi external USB drive I have to unmount all of the partitions on the said drive. To make things easier when formatting my drive I named (labelled) all of its partitions so that the names (labels) begin with 'HIT'.
For further reading please refer to the bug report (the lack of either "Safely remove" or "Eject" is a bug in Ubuntu 12.10):
https://bugs.launchpad.net/ubuntu/+source/udisks2/+bug/1067876
Don't forget to mark 'This bug affects me' in the upper portion of the page.
There seems to be a bug report about the missing option.
@k-k-patel Even if "eject" and "safely remove" are virtually the same for external hard drives, none of the two are available. Only "unmount" is offered.
@hari @isoma No "unmount" and "eject/safely remove" are not the same and even for an external hard drive "eject/safely remove" is not subsumed by "unmount". For instance, consider a drive with two partitions. If the "user" unmounts one of them, the other one will remain mounted, and, as a result, if the user unplugs the drive, they face a data loss on the second partition. On the other hand, if the user "ejects/safely removes" the first partition, both will get unmounted.