dephtu@dephtop:~$ sudo modprobe raid1
dephtu@dephtop:~$ cat /proc/mdstat
Personalities : [raid1] 
unused devices: <none>
dephtu@dephtop:~$ sudo mdadm --create /dev/md0 --chunk=64 --level=raid1 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm: /dev/md0 does not appear to be an md device