Step-by-step guide
Check devices installed using 'fdisk -l'
Example: [root@admin]# fdisk -l
sudo mdadm --manage /dev/md# --add /dev/sdx#
Example: [root@admin]# sudo mdadm --manage /dev/md1 --add /dev/sda3
Check status in /proc/mdstat
Example: Personalities : [raid1] [raid6] [raid5] [raid4] md127 : active raid5 sdh1[6] sdg1[4] sdf1[3] sde1[2] sdd1[1] sdc1[0] 1464725760 blocks level 5, 64k chunk, algorithm 2 [6/5] [UUUUU_] [===>.................] recovery = 14.2% (41598211/292945152) finish=125.5min speed=33440K/sec