In this chapter, we learned about the concepts of high availability: redundancy, failover, and load balancing. We also learned how to configure link-layer redundancy by creating bonding interfaces, as well as how to set up redundant routes at the network layer. To ensure transport layer redundancy, we learned how to configure the LVS subsystem by hand with
ipvsadm or using Keepalived and also learned how to provide failover for load-balancing nodes using VRRP. Finally, we took a brief look at HAProxy as an application layer load-balancing solution for web servers.
In the next chapter, we will learn about managing Linux systems with configuration automation tools.