mdadm –create /dev/md0 –chunk=4 –level=0 –raid-devices=2 /dev/sda4 /dev/sdb1
mdadm -A <md-device> <components> –homehost=<somestring> –update=homehost
sudo nano /etc/udev/rules.d/85-mdadm.rules
Then find this text, which should be the only uncommented text:
SUBSYSTEM=="block", ACTION=="add|change", ENV{IDFSTYPE}=="linux_raid*", \
RUN+="watershed /sbin/mdadm --assemble --scan --no-degraded"
Replace the --no-degraded option with the --run option like so:
SUBSYSTEM=="block", ACTION=="add|change", ENV{IDFSTYPE}=="linux_raid*", \
RUN+="watershed /sbin/mdadm --assemble --scan --run"
Then propagate the changes to every initrd with the following command:
sudo update-initramfs -u -k all