Comment 7 for bug 1089195

This is really annoying bug. Even experienced user who never encountered a problem with consumed inodes will spend a lot of time finding the cause of the problem. The error message "No space left on device" does not suggest that the problem is with inodes.

The update process should certainly remove very old kernels automatically by default or show an explanatory warning.

There are many examples of users which faced this problem:
http://askubuntu.com/q/317763/67132
http://askubuntu.com/q/388449/67132
http://ubuntuforums.org/showthread.php?t=2039786
http://ubuntuforums.org/showthread.php?t=2206534

See also related Bug #690911 Installation without formatting fails to remove old kernels

Attempts (certainly imperfect) to remove old kernels automatically:
https://help.ubuntu.com/community/Lubuntu/Documentation/RemoveOldKernels#Automatic
http://ubuntuforums.org/showthread.php?t=1961409&page=3&p=11859290#post11859290