Comment 36 for bug 573477

The problem exists in the initramfs boot scripts. They do not fire --assemble. To fix this, I removed the package hook and scripts and replaced them with those provided in the debian package. The debian scripts are much better and not sure why ubuntu does not use those by default anyway.

here is a quick fix - assumes mdadm is config and working

#Remove ubuntu package scripts:
rm /usr/share/initramfs-tools/hooks/mdadm
rm /usr/share/initramfs-tools/scripts/mdadm-functions
rm /usr/share/initramfs-tools/scripts/init-premount/mdadm
rm /usr/share/initramfs-tools/scripts/local-premount/mdadm

#Extract / cp files from deb:
cp mdadm_3.2.5-3_amd64/usr/share/initramfs-tools/hooks/mdam /usr/share/initramfs-tools/hooks/mdadm
cp mdadm_3.2.5-3_amd64/usr/share/initramfs-tools/scripts/local-top/mdadm /usr/share/initramfs-tools/scripts/local-top/mdadm

#Then update initramfs
update-initramfs -vck all