Starting with the stress test, we got a sense of how good a given Cassandra setup will do under an artificially standardized load. This may or may not reflect the particular use case that you are planning to use Cassandra for. You may tweak the stress test parameters to get closer to your test case. If needed, you should simulate a load that represents the load condition that you are expecting on Cassandra. This will give you a baseline for what to tune. It will be helpful to keep some profiling running at the OS level to gauge what resource is getting depleted—things such as JConsole, nodetool cfstats, and tpstats. Linux commands such as iostats, vmstats, top, df, and free can help to look through what's getting heated up or whether everything is okay. We will see these tools in more detail in Chapter 6, Managing a Cluster – Scaling, Node Repair, and Backup, and Chapter 7, Monitoring.

With the performance tuned, the next step is the maintenance of a cluster. In the next chapter, we will see different ways to tackle everyday DevOps problems such as how to scale up when traffic is high, how to replace a dead node, and other issues. In later chapters, we will see how to keep tabs on various performance statistics. We will see that what you have learned in this and the next couple of chapters will help when troubleshooting an issue.