Understanding the Limits of Virtualization

One of the benefits of virtualization that has led the technology to be so popular is the capability to consolidate many physical servers onto a single virtual host. This is possible because most physical servers rarely utilize all their physical processor, memory and storage capacity, and I/O. So, for example, if you have four physical servers each using around 20% of their CPU, you could consolidate them onto one physical server of the same CPU specification and not expect to impact performance perceivably (assuming that storage, network, and memory are also specified appropriately).