Comment 11 for bug 150872

Just so I understand, it sounds to me like when I install Ubuntu from a USB cdrom drive it will add an entry to /etc/fstab for that removable drive. However, once you remove that drive from the system (as you may have only wanted to use it for the install) the drive is now invalid. Can you explain further why apt-cdrom needs an invalid entry in /etc/ftab?

Can the installer check the value of /sys/block/sr*/removable and not add the drive to /etc/fstab if the value is "1"? What is the effect on apt-cdrom? I suppose we need to file a bug against apt-cdrom to support installation from installation media that are not necessarily a CD-ROM (such as a USB key) or prompt the user to insert media, detect the insertion of a device and check that device for the installation media.

Ok, I'm sure that is not easy, but I'm just trying to give alternatives.