VKernel, now part of DELL has released a paper titled:"Best Practices for Oversubscription of CPU, Memory and Storage in vSphere Virtual Environments". The paper which can be downloaded after registration contains 13 pages and is written by Scott D. Lowe and provides insight in the pros and cons of oversubscription of Processing, Memory and Storage resources. Scott also details how far oversubscription should be taken before it becomes dangerous.
Scott uses vOps Server Explorer, for which VKernel recently released version 6 as the tool to monitor the resources. He details the metrics to watch when oversubscribing and gives some insight in just how far resource overcommitment can be taken.
--> Please see the rest on the blog : http://virtualization.info/en/news/2012/11/paper-best-practices-for-oversubscription-of-cpu-memory-and-storage-in-vsphere-virtual-environments.html