root@ubuntu:/# dpkg-reconfigure mdadm
runlevel:/var/run/utmp: No such file or directory
W: mdadm: failed to load MD subsystem.
 Removing any system startup links for /etc/init.d/mdadm-raid ...
update-initramfs: deferring update (trigger activated)
/usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?).
runlevel:/var/run/utmp: No such file or directory
Processing triggers for initramfs-tools (0.103ubuntu4.6) ...
update-initramfs: Generating /boot/initrd.img-4.4.0.62-generic
grep: /boot/config-4.4.0.62-generic: No such file or directory
WARNING: missing /lib/modules/4.4.0.62-generic
Device driver support needs thus be built-in linux image!
depmod: ERROR: could not open directory /lib/modules/4.4.0.62-generic: No such file or directory
depmod: FATAL: could not search modules: No such file or directory
depmod: WARNING: could not open /tmp/mkinitramfs_s62t0U/lib/modules/4.4.0.62-generic/modules.order: No such file or directory
depmod: WARNING: could not open /tmp/mkinitramfs_s62t0U/lib/modules/4.4.0.62-generic/modules.builtin: No such file or directory