VMware white-papers are my primary source of information. Almost every single one of them contains valuable information. VMware  just released a brand new white paper titled “Understanding Memory Resource Management in VMware ESX Server” which is most definitely worth reading.

Download:
http://www.vmware.com/files/pdf/perf-vsphere-memory_management.pdf

Description: VMware® ESX™ is a hypervisor designed to efficiently manage hardware resources including CPU, memory, storage, and network among
multiple concurrent virtual machines. This paper describes the basic memory management concepts in ESX, the configuration
options available, and provides results to show the performance impact of these options.