I have created a RAID-10 array using mdadm, but it does not completely
start on boot. Th RAID-10 array is /dev/md3 and is comprised of two
sub-arrays, /dev/md1 and /dev/md2. The two sub-arrays start on boot,
but /dev/md3 never starts; so I have to run 'mdadm -A /dev/md3'.

My mdadm.conf file defines all three arrays. I suspect this has
something to do with the fact that /dev/md3 is not comprised of
physical devices, but logical 'md' devices.

Any thoughts?