Comment 37 for bug 990913

couple of minor elaborations to the above:

update-initramfs -u

so the edited mdadm.conf gets into the initramfs

and in /etc/rc.local:

mdadm --assemble --config=partitions --no-degraded --scan

so it doesn't try to start the array if it would be degraded, thus probably requiring a rebuild - as the likely reason for that at this stage is because the update-initramfs step was missed above; or some other failure to start the sub-arrays. :-}