headless ~ # cat /proc/mdstat 
Personalities : [raid0] [raid1] 
md2 : active raid0 sda1[0] sdd1[3] sdc1[2] sdb1[1]
      624992256 blocks 64k chunks
      
md1 : active raid1 hdb3[1] hda3[0]
      75939136 blocks [2/2] [UU]
      
md0 : active raid1 hdb1[1] hda1[0]
      248896 blocks [2/2] [UU]
      
unused devices: <none>