Create a partition on /dev/sdc with 60801 cylinders that is type Linux Software Raid (fd)

echo "0 60801 fd" | sfdisk /dev/sdc Create a big RAID5 array with with four partitions (--auto creates the /dev/mdX device) mdadm --create /dev/md8 --raid-devices=4 --level=5 --auto=yes /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 If you mess up and you want to blow the whole array away and start over mdadm --stop /dev/md8