After migrating a software RAID 5 to Ubuntu LTS 12.04, the system wouldn't come up again after rebooting. I believe Chris Siebenmann to splendidly have analysed [1] the problem: a race condition with udev losing the race. His solution is to: Change /usr/share/initramfs-tools/scripts/mdadm-functionsas follows: degraded_arrays() { + udevadm settle mdadm --misc --scan --detail --test >/dev/null … Continue reading mdadm woes →