The installer fails if there are already superblocks on your disks. They get set (partly) assembled and the installer is not capable of showing or handling these.
Try writing zeros to your disk or mdadm --stop and --zero-superblock from another console. -- grub-installer fails to install on a raid1 array https://bugs.launchpad.net/bugs/527401 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
