I've finally solved this in my case: After detecting the second disk, udev triggers a mdadm --assemble --scan as it should. This failed to pick up the new disk. Removing num-devices=, level= and uuid= settings from /etc/mdadm/mdadm.conf resolved this problem. My /etc/mdadm/mdadm.conf now reads:
I've finally solved this in my case: After detecting the second disk, udev triggers a mdadm --assemble --scan as it should. This failed to pick up the new disk. Removing num-devices=, level= and uuid= settings from /etc/mdadm/ mdadm.conf resolved this problem. My /etc/mdadm/ mdadm.conf now reads:
DEVICE /dev/hda1 /dev/hda2 /dev/sda2 /dev/sda3
ARRAY /dev/md0 devices= /dev/hda1, /dev/sda2 /dev/hda2, /dev/sda3
ARRAY /dev/md1 devices=
A dpkg-reconfigure mdadm later the problem was gone. Together with the evms removal this is probably worth it to be put into an upgrade guide.