Linked from: Configuring Partitions and RAID
RAID 6 require 4 disks at a minimum. Configure RAID 6 in the same manner as RAID 5 - Redundancy but select RAID 6 instead during the RAID creation process.
search?q=clearos%2C%20clearos%20content%2C%20clearos7%2C%20userguide%2C%20categoryinstallation%2C%20subcategoryinstaller%2C%20subsubcategoryfullinstalliso%2C%20maintainer_dloper&btnI=lucky