I think the solution is in: Bug report: 83231 https://launchpad.net/ubuntu/+source/initramfs-tools/+bug/83231
the "udevsettle --timeout 10" at the end of /usr/share/initramfs- tools/scripts/init-premount/udev works too. -- boot-time race condition initializing md https://launchpad.net/bugs/75681 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs