abundance ~ # mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm: size set to 80035712K
mdadm: array /dev/md1 started.
abundance ~ # cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10]
md1 : active raid1 sdb1[1] sda1[0]
      80035712 blocks [2/2] [UU]
      [=>...................]  resync =  5.5% (4450944/80035712) finish=21.3min speed=59094K/sec

unused devices: <none>