Hardware design should come after you have determined how many resources you need and how many virtualization hosts you plan to deploy. In some environments, the hardware may be preselected based on the vendor contracts. Other environments may have pre-existing hardware due to early purchases, surplus, or repurposing other hardware. Even if the hardware is preexisting, design the environment for what is needed first, then compare with the hardware available. If there are not enough resources, you can either trim the design to match, request additional hardware, or possibly phase in the environment to the resources available (design for 1,000 users but only deploy for 500 users until more hardware is acquired).