You have several options to help in debugging your application.
On the client side, besides using the Eclipse debugger, you can monitor different metrics that the Java driver collects by default, (for example, connections to hosts). You can also implement your own metric objects and register them with the driver.
- enable tracing
- adjusting the log4j configuration for finer logging granularity
If you are using DataStax Enterprise, you can store the log4j messages into a Cassandra cluster.