What exactly do you mean when you say "emergency mode"? The expected behavior, when you boot Ubuntu and have a filesystem referenced in /etc/fstab for which the device is absent, is that the system will prompt, via plymouth, whether to continue waiting for the filesystem or to skip mounting it. This should be the case up through Ubuntu 14.10. For Ubuntu 15.04, with the switch to systemd the behavior will be different; but should still not result in the system booting to anything that could be considered "emergency mode".
** Changed in: mountall (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1485708 Title: fstab entry causes emergency mode to come up To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mountall/+bug/1485708/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs