mdadm zero-superblock to solve md device created on root device -
mdadm zero-superblock to solve md device created on root device
It is possible to tell mdadm to create an md device on a raw disk even though it will give you an error, it writes a superblock and this corrupts the partition table which can result in your system not booting.
To fix it just zero the super-block on the offending device that you made the mistake in.
mdadm --zero-superblock /dev/sda
It is also a way of starting fresh if you wanted to create a new array.