Yes, VMAX can be both Open, Mainframe and AS400 in the same box. The physical disks can contain both CKD and FBA devices on the same physical disk / disk group (thick).Seperate pools (data devices) are required for thin, but the pools can reside on the same physicals. VMAX  can also share engines and directors between MF and OS. You can have Ficon and FC on the same director. An IO module on a director can only be Ficon or other. A director has 2 IO modules and therefore can contain both open and MF.