Raid 1 + LVM

1. # mdadm --create --verbose --level=1 --metadata=1.2 --raid-devices=2 /dev/md/0 /dev/sda1 /dev/sdb1
2. # mdadm --create --verbose --level=1 --metadata=1.2 --raid-devices=2 /dev/md/1 /dev/sdc1 /dev/sdd1
3. Add array to configuration and assemble, see arch wiki
4. # pvcreate /dev/md/0
5. # pvcreate /dev/md/1
6. # vgcreate vg0 /dev/md/0
7. # vgextend vg0 /dev/md/1