You can add, change, or configure virtual machine memory resources or options to enhance virtual machine performance. You can set most of the memory parameters during virtual machine creation or after the guest operating system is installed. Some actions require that you power off the virtual machine before changing the settings.

Memory resource configuration is distinct from the virtual hardware memory size, which you configure on the Hardware tab. The memory resource setting determines how much of the host's memory is allocated to a virtual machine. The virtual hardware memory size determines how much memory applications that are running inside the virtual machine have available to them. A virtual machine cannot benefit from more memory resources than its configured virtual hardware memory size. The ESXi host caps memory resource use to the maximum useful for the virtual machine, so you can accept the default of Unlimited memory resources.