The virtual machines per core (VMs / core) ratio is a measurement unit that virtualisation vendors use with extreme prudence to provide a rough idea of the server consolidation level that can be achieved on their hypervisors.
This ratio can be greatly influenced by several factors. The most important one is the kind of application workload that will run inside guest operating systems.
Depending on this element alone, some customers may end up having as low as 2:1 ratios while others may experience much higher values, so the best answer to any question around this topic is “it depends”.
Officially, the company says that its hypervisor can support an average consolidation ratio of 8 VMs / core, a number that several customers report as a realistic one mostly in VDI environments.
VMware may be about to double this value, reaching 16 VMs / core, with upcoming versions of its desktop virtualisation platform View based upon the Intel Nehalem processor.