In this chapter, you learned some of the most important concepts about high availability and failover. You also learned the different options available to build a redundant OpenStack architecture with a robust resiliency. You will know how to diagnose your OpenStack design by eliminating any SPOF across all services. We highlighted different open source solutions out of the box to arm our OpenStack infrastructure and make it as fault-tolerant as possible. Different technologies were introduced, such as HAProxy, database replication such as Galera, Keepalived, Pacemaker, and Corosync. This completes the first part of the book that aimed to cover different architecture levels and several solutions to end up with an optimal OpenStack solution for a medium and large infrastructure deployment.

Now that we have crystallized the high availability aspect in our private cloud, we will focus on building a multinode OpenStack environment in the next chapter and dive deeper into orchestrating...