I have seen this behaviour a number of times on Ubuntu and Debian.
After you create the array you need to update mdadm.conf. However, this is not enough as you also need to update the version in initrd.img. This might happen automatically if you subsequently do some updates. I find the easiest way to force it is to call
I have seen this behaviour a number of times on Ubuntu and Debian.
After you create the array you need to update mdadm.conf. However, this is not enough as you also need to update the version in initrd.img. This might happen automatically if you subsequently do some updates. I find the easiest way to force it is to call
dpkg-reconfigure mdadm