Rescan md-device
mdadm --assemble --scan
Stop md-device
Stop all service using device, samba, nfs
mdadm --manage --stop /dev/md0
Readd md-device
mdadm --manage --add /dev/md0 /dev/sdc2
Force Assemble
sudo mdadm –assemble –run –force /dev/md127 /dev/sd[abdc]3