EDIT: It appears that this might be an inherent issue with the .9 superblock version. Figures that I would only be able to find these links after I posted here.
Recently, I added to new disks to a machine. I created one partition on each drive, and used software raid to set up a raid1 between the partitions. However, for some reason after I add the partitions to the array, mdadm also detects the superblock in the underlying block devices. This causes a lot of problems during boot, as udev tries to assemble arrays incrementally and stumbles on /dev/sda before /dev/sda1. As you can see below, only md3 suffers from this problem. It was assembled with
mdadm -A /dev/md3 /dev/sda1 /dev/sdb1. Have I set up these partitions incorrectly somehow?
root@blaster:/# mdadm --examine --verbose --scan ARRAY /dev/md3 level=raid1 num-devices=2 UUID=33868dc0:becdb6b6:8b9f62c7:cb89d2ee spares=2 devices=/dev/sdb1,/dev/sdb,/dev/sda1,/dev/sda ARRAY /dev/md0 level=raid1 num-devices=2 UUID=866cc7e5:f18b48c0:539d4f3e:4592bf76 devices=/dev/sdd1,/dev/sdc1 ARRAY /dev/md1 level=raid1 num-devices=2 UUID=550101be:d1fac9c9:48c0e818:59501087 devices=/dev/sdd2,/dev/sdc2 ARRAY /dev/md2 level=raid1 num-devices=2 UUID=7783bbb3:6e381768:8b9f62c7:cb89d2ee devices=/dev/sdf1,/dev/sde1