RAID 10

$ mdadm --create --verbose /dev/md0 --level=10 --raid-devices=2 /dev/sda2 /dev/sdb2

$ cat /proc/mdstat
Personalities : [raid1] [raid10]
md0 : active raid10 sdb2[1] sda2[0]
      52396032 blocks super 1.2 2 near-copies [2/2] [UU]
      [>....................]  resync =  0.7% (399104/52396032) finish=6.5min speed=133034K/sec

unused devices: <none>
$ cat /proc/mdstat
Personalities : [raid1] [raid10]
md0 : active raid10 sdb2[1] sda2[0]
      52396032 blocks super 1.2 2 near-copies [2/2] [UU]

unused devices: <none>