The primary concept that vSphere is built around is taking an individual computer, network and disk resources, and combining those into a pool that can be shared by numerous virtual machines. Because of this base concept, resource pools in vSphere are an important concept to understand and administer.

In this chapter, you will look at the basic management of resource pools using PowerCLI. Resource pools have several settings that determine how virtual machines are given access to the available resources. In an environment where there is no contention, virtual machines can consume all of the resources that they request. However, as your environments grow, contention for resources develops, and resource pools are used to set priorities and limits on how much a virtual machine can consume.

Reservations are settings for virtual machines so they are guaranteed a certain amount of CPU or memory regardless of how much contention or slowdown it might create on other virtual machines...