Having the same problem with an upgrade from 12.04 to 14.04 - had to fall back from grub2 to grub, since grub2 seems to have issues with software raid, then ran into this issue with mdadm freezing up during configuration.
Having the same problem with an upgrade from 12.04 to 14.04 - had to fall back from grub2 to grub, since grub2 seems to have issues with software raid, then ran into this issue with mdadm freezing up during configuration.