If you choose to deploy VMware Horizon 8 in a VMware virtualized environment some minimum version of the virtualization software is required.
If you are using vSphere, you must use a supported version of vSphere ESX/ESXi hosts and vCenter Server.
For details about which versions of VMware Horizon 8 are compatible with which versions of vCenter Server and ESXi, see the VMware Product Interoperability Matrix at http://www.vmware.com/resources/compatibility/sim/interop_matrix.php.