I kept getting these error message during the boot process and also after issuing the command ‘sudo update-initramfs -u’:
W: mdadm: unchecked configuration file: /etc/mdadm/mdadm.conf
W: mdadm: please read /usr/share/doc/mdadm/README.upgrading-2.5.3.gz .
W: mdadm: no arrays defined in configuration file.
W: mdadm: falling back to emergency procedure in initramfs.
The mdadm-package is needed for software raid array. If you don’t have a raid array you can solve this problem simply by removing the mdadm package: ‘sudo apt-get remove mdadm’. More information is at launchpad.net.