Scan a system for RAID arrays and save findings so the array reappears across reboots:

# mdadm --detail --scan >> /etc/mdadm/mdadm.conf

Create a RAID5 array out of sdm1, sdj1, and sdk1 (all partitioned with raid-autodetect partitions)

# mdadm --create /dev/md1 --level=5 --raid-devices=3 /dev/sd[mjk]1

Create a RAID1 array

# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sd[ts]1

Remove a RAID array

# mdadm --stop /dev/md1
# mdadm --zero-superblock /dev/sd[ts]1