One of the foundations of OpenStack is that it was built to run on generic commodity hardware and is intended to scale out horizontally very easily. Scaling horizontally means adding more servers to get the job done. Scaling vertically means getting larger, more specialized servers. Whether the servers you run have a handful of processors and a few gigabytes of RAM, or double digits of processors and RAM approaching or exceeding triple digits, OpenStack will run on your servers. Further, whatever assortment of servers of varying horsepower you have collected, they can all be joined into an OpenStack cluster to run the API services, service agents, and hypervisors within the cluster. The only hard requirement is that your processors have virtualization extensions built into them, which is pretty much a standard feature in most modern-day processors. In this chapter, we will look at the process of scaling an OpenStack cluster horizontally on the control, network...