Comment 32 for bug 158918

> what I don't get is why a broken array (with no mount point specified) would result in an unbootable system.

This is again the glorious mdadm thing of setting up arrays according to unreliable superblock information (device "minor" numbers, labels, hostnames) combined with the idea of fixing the unreliability by limiting array assembly with mdadm.conf (PARTITIONS, ARRAY, HOMEHOST lines) and thus forcing setup tools and admins to create mdadm.conf files leading to exact the same problems.

The only thing mdadm can and should rely on when assembling is the high probability of uniqueness of UUIDs (not on admins or tools or install scripts to set up mdadm.conf). Bug #136252