Booting from SAN is possible, provided that the HBA(s) present this ability to the BIOS. In other words, provided the OS can be booted via the LUN(s) provided by the HBA(s) then there should be no problem. When extra LUN(s) are presented to the hypervisors to use as shared storage, RHV will only allow un-used LUNs to be accepted into the storage domain, therefore its possible to both boot from SAN and use the same storage paths for shared storage in RHV.