MySQL’s built-in replication is the foundation for building large, high-performance applications on top of MySQL, using the so-called “scale-out” architecture. Replication lets you configure one or more servers as replicas^[144] of another server, keeping their data synchronized with the master copy. This is not just useful for high-performance applications—it is also the cornerstone of many strategies for high availability, scalability, disaster recovery, backups, analysis, data warehousing, and many other tasks. In fact, scalability and high availability are related topics, and we’ll be weaving these themes through this chapter and the next two.

In this chapter, we examine all aspects of replication. We begin with an overview of how it works, then look at basic server setup, designing more advanced replication configurations, and managing and optimizing your replicated servers. Although we generally focus a lot on performance in this book, we are equally concerned with correctness and reliability when it comes to replication, so’ll we show you how replication can fail and how to make it work well.