The number of virtual machines that can be run on one server actually depends on the physical box configuration—the memory, processor speed etc.—and resource demands of the applications on each virtual server. For example with CPU-intensive workloads, memory becomes a significant factor in performance and hence in overall VM capacity. In fact with very powerful boxes, you usually run out of memory and disk I/O before all the CPU power is exhausted.

A more powerful server and lower application resource demand means you can host a greater number of virtual machines. Conversely, lower box power and higher application resource demand mean fewer virtual machines per physical server.

That’s why at Mosaic as a first step in any virtualization we give our customers an informal VM Capacity Discovery session. We can give a first level assessment of what level of consolidation to expect.