Perhaps more important than the configuration of the VM Server farm is sizing and capacity planning for the farm. If the VM Server farm is undersized, performance and capacity will suffer and your system will not run at the desired level of service or capacity.
Sizing is the act of determining the amount of hardware needed for an anticipated workload.
Capacity planning is the act of determining the amount of additional hardware necessary to add to an existing system in order to meet future workloads.
Both sizing and capacity planning are as much an art form as a science. There is mathematics involved, monitoring and analyzing of existing workloads, and a lot of extrapolation. Probably more so than ...