VMware vSphere vCenter Server 4.0 - Manual

vSphere Resource Management Guide
ESX 4.0
ESXi 4.0
vCenter Server 4.0
This document supports the version of each product listed and
supports all subsequent versions until the document is replaced
by a new edition. To check for more recent editions of this
document, see
http://www.vmware.com/support/pubs .
EN-000107-02