Superblock general info
http://www.bellevuelinux.org/superblock
Convert to RAID 1
http://wiki.archlinux.org/index.php/Convert_a_single_drive_system_to_RAID
http://wiki.hpc.ufl.edu/index.php/System_mirror
http://www.howtoforge.com/software-raid1-grub-boot-debian-etch-p2