philipp@elrond:~$ cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid5 sdb1[2] sdd1[1] sdc1[0]
      1465151808 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
      
unused devices: <none>
philipp@elrond:~$ sudo mdadm --detail --scan
ARRAY /dev/md0 level=raid5 num-devices=4 metadata=00.90 UUID=a7612fc7:48426af4:9615a9b1:92f14bda
philipp@elrond:~$