For the benefit of those stumbling on this bug looking for a work-around, just doing "mdadm --run /dev/md0" (assuming the array in question is /dev/md0) should be sufficient to fail the missing disk and making the array run in degraded mode. You then reboot, and the system should come up.
For the benefit of those stumbling on this bug looking for a work-around, just doing "mdadm --run /dev/md0" (assuming the array in question is /dev/md0) should be sufficient to fail the missing disk and making the array run in degraded mode. You then reboot, and the system should come up.