Generating grub configuration file ...
  Couldn't find device with uuid 1lR3fZ-Vz6F-I1u9-fIu6-Xgsz-507l-UfPs8H.
  Couldn't find device with uuid 1lR3fZ-Vz6F-I1u9-fIu6-Xgsz-507l-UfPs8H.

(..)

W: mdadm: the array /dev/md/backup with UUID 1748672f:ddf47a81:9db19a1b:33c1e793
W: mdadm: is currently active, but it is not listed in mdadm.conf. if
W: mdadm: it is needed for boot, then YOUR SYSTEM IS NOW UNBOOTABLE!
W: mdadm: please inspect the output of /usr/share/mdadm/mkconf, compare
W: mdadm: it to /etc/mdadm/mdadm.conf, and make the necessary changes.