RAID management utility.
Create array
sudo mdadm --create /dev/md/MyRAID --level raid_level --raid-devices number_of_disks /dev/sdXN
Stop array
sudo mdadm --stop /dev/md0
Mark disk as failed
sudo mdadm --fail /dev/md0 /dev/sdXN
Remove disk
sudo mdadm --remove /dev/md0 /dev/sdXN
Add disk to array
sudo mdadm --assemble /dev/md0 /dev/sdXN
Show RAID info
sudo mdadm --detail /dev/md0
Reset disk by deleting RAID metadata
sudo mdadm --zero-superblock /dev/sdXN