Learning MySQL, 2nd Edition

Chapter 12. Monitoring MySQL Servers

Monitoring can be defined as observing or checking the quality or progress of something over a period of time. Applying that definition to MySQL, what we observe and check are the server’s “health” and performance. Quality, then, would be maintaining uptime and having performance meet desired levels. So really, monitoring is a continuous effort to keep things under observation and control. Usually it’s thought of as something optional, which may not be needed unless there’s a particularly high load or high stakes. However, just like backups, monitoring benefits almost every installation of any database.

We think that having monitoring in place and understanding the metrics you’re getting from it is one of the most important tasks for anyone operating a database system—probably just after setting up proper verified backups. Like operating a database without backups, failing to monitor your database is dangerous: what use is a system that provides unpredictable performance and may be “down” randomly? The data may be safe, but it might not be usable.

In this chapter, we’ll try to give you a foundation for understanding how to monitor MySQL efficiently. This book is not called High Performance MySQL, and we won’t be going into depth on the specifics of exactly what different metrics mean or how to perform a complex analysis of a system. But we will talk about few basic metrics that should be checked regularly in every MySQL ...