> cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid5 sdb[0] sdd[3] sdc[1]
      3907024768 blocks level 5, 64k chunk, algorithm 2 [3/2] [UU_]
      [==============>......]  recovery = 71.0% (1387847968/1953512384) finish=587.6min speed=16041K/sec

unused devices: <none>