$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sdb2[2](F) sda2[0]
      4982720 blocks super 1.2 [2/1] [U_]

md0 : active raid1 sdb1[2](F) sda1[0]
      483266368 blocks super 1.2 [2/1] [U_]

unused devices: <none>