mdadm

create volumes

Find the disks:

lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT

Do we already have raid volumes?

cat /proc/mdstat

If yes unmount and stop:

umount /dev/md0
mdadm --stop /dev/md0

Cleanup the headers for each disk:

mdadm --zero-superblock /dev/sda
mdadm --zero-superblock /dev/sdb

Create a raid volume:

mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/sda /dev/sdb

Levels are the classical ones: 0 stripes, 1 mirror, 5 etc

Then

mkfs.ext4 -F /dev/md0
mount /dev/md0 /mnt/md0

And store the results:

mdadm --detail --scan | tee -a /etc/mdadm/mdadm.conf
update-initramfs -u
echo '/dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0' | tee -a /etc/fstab