As the old systems adage goes, a service doesn’t exist unless it’s monitored. In this chapter we are going to cover the basics of monitoring Cassandra. This includes file-based logging, inspection of the JVM, and monitoring of Cassandra itself.
Under the covers, Cassandra uses the standard Java log library Log4j. Log4j is another Apache project that enables the capability to control the granularity of log statements using a configuration file. If you want to find out more about what is going on on a particular node than what nodetool and JMX MBeans (which we will cover in more detail later in the chapter) are telling you, then you can change the logging levels.
As a front end to the Log4j back end, Cassandra uses Simple ...