Asus RS120-E4/PA4 - Manual (Page 113)

ASUS RS120-E4/PA4 6-7
4. Select all the drives required for the RAID set, then press <Enter>. The
configurable array appears on screen.
5. Press <F10>, select the configurable array, then press <SpaceBar>.
The logical drive information appears including a Logical Drive menu that
allows you to change the logical drive parameters.