MX4J warning message during DataStax Enterprise installation 

MX4j provides an HTML and HTTP interface to JMX and is not necessary to run DataStax Enterprise.

The DataStax Enterprise Help Center also provides troubleshooting information.

When DataStax Enterprise loads, you may notice a message that MX4J will not load and that mx4j-tools.jar is not in the classpath.

You can ignore this message. MX4j provides an HTML and HTTP interface to JMX and is not necessary to run DataStax Enterprise.

DataStax recommends using OpsCenter. It has more monitoring capabilities than MX4J.