https://askubuntu.com/questions/680122/cant-boot-mdadm-create-group-disk-not-found
https://askubuntu.com/questions/529228/mdadm-raid1-home-server-system-disk-error-incrementally-starting-raid-arrays-md https://serverfault.com/questions/768239/ubuntu-raid-cant-boot-mdadm/768264v http://ubuntu.5.x6.nabble.com/raid-not-booting-td1533824.html
