As we mentioned before, OpenStack is designed to be scalable, but not infinitely scalable. There are three different techniques architects can use to segregate an OpenStack cloud: regions, cells, and availability zones. In this section, we'll walk through how each of these concepts maps to hypervisor topologies.
Regions, cells, and availability zones
Regions
From an end user's perspective, OpenStack regions are equivalent to regions in Amazon Web Services. Regions live in separate data centers and are often named after their geographical location. If your organization has a data center in Phoenix and one in Raleigh, you'll have at least a PHX and an RDU region. Users who want to geographically disperse their...