Monitoring cassandra disk space with jmx

Question

When I tried to monitor Cassandra_node with JMX, I had a problem.

In detail, I got a negative value from jmx["org.apache.cassandra.metrics:type=Storage,name=Load","Count"].

In Cassandra Wiki, the definition of this metrics is:

Total disk space used (in bytes) for this node

Is it possible to get a negative value from this metrics? and why?

Answer 1

Yes its possible. It depends a bit on version but there were some bugs like CASSANDRA-8205 and CASSANDRA-7239 in particular around the load. If its operating like it should, those will be accurate though.

You can always drop down to OS level and monitor it by looking at du on the data directory.