For me no amount of settings in mdadm.conf worked. --examine looks fine on both my partitions participating in a raid 1 volume.
I played with DEVICE, HOMEHOST, ARRAY and tried all kind of suggestions. The only way I could get my raid1 array to assemble on bootup was doing this: root@jamaica:~# cat /lib/udev/rules.d/85-mdadm.rules | grep mdadm # This file causes block devices with Linux RAID (mdadm) signatures to # automatically cause mdadm to be run. RUN+="/sbin/mdadm /dev/md0 --assemble --add /dev/sdb2 /dev/sdc2" #RUN+="/sbin/mdadm --incremental $env{DEVNAME}" Plus: root@jamaica:~# update-initramfs -u -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/541058 Title: [->UUIDudev] mdadm fails to automatically assemble raid during boot (without mdadm.conf) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/541058/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs