In order to debug the cassandra server from your favorite IDE. You need to add the following into cassandra-env.sh located in apache-cassandra-1.1.0/conf directory.
JVM_OPTS="$JVM_OPTS -Xdebug" JVM_OPTS="$JVM_OPTS -Xnoagent" JVM_OPTS="$JVM_OPTS -Djava.compiler=NONE" JVM_OPTS="$JVM_OPTS -Xrunjdwp:transport=dt_socket,server=y,address=5005,suspend=n"
After adding this, once you start the server you can see the following line printed in cassandra console
"Listening for transport dt_socket at address: 5005"
This the port that you specified in JAVA_OPTS. You can change it to some other value as you want.
Now configure your IDE to run on debug mode.
Now you can debug the apache cassandra server from your favorite IDE :)