Please upgrade to 3.3-2ubuntu7.2 and try to reproduce again. That version in xenial-updates has fixed some degraded boot problems.
** Changed in: mdadm (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1631037 Title: not possible to boot from a degraded raid1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1631037/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs