Comment 9 for bug 652327

/usr/share/mdadm/mkconf gives me:
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
DEVICE /dev/sdb1 /dev/sdc1

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon where to send mail alerts
MAILADDR root

# definitions of existing MD arrays
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=21fd4b98:0c4a255f:d4c030d5:a9b8b27a

This also works (maybe the DEVICE stuff is supposed to be UUID's ?)... Anyway both configurations work