Cassandra is all about speed—quick installation, fast reads, and fast writes. You got your application optimized, minimized the network trips by batching, and denormalized the data to get maximum information in one request. However, the performance is not what you read over the Web and in various blogs. You start to doubt whether the claims actually measure. Hold on! You may need to tune things up.

This chapter will discuss how to get a sense of a Cassandra cluster's capacity and have a performance number handy to back up our claims. It then dives into the various settings that affect read and write throughput, a couple of JVM tuning parameters, and finally, a short discussion on how scaling systems horizontally and vertically can improve the performance.