1. A method of operating a computer system comprising a plurality of physical computer nodes, a plurality of virtual machines executing on the plurality of physical computer nodes, and a monitor that monitors resources in the computer system, wherein each of the plurality of virtual machines comprises a virtual representation of a computer system, the method comprising: (A) configuring at least one resource group that comprises at least one of the plurality of virtual machines, so that the at least one of the plurality of virtual machines can be monitored by the monitor.