If its the RMI horror ( registry port + actual port ) you are worried about, enabling MX4J in cassandra-env.sh for the HTTP transport (
http://wiki.apache.org/cassandra/Operations#Monitoring_with_MX4J ) could help although i never used it myself. Or you can just throw in the Jolokia JVM agent http://www.jolokia.org
which will do roughly the same
i'm not aware of the hit rate or any of the other cf/system metrics being exposed over anything other than JMX, sorry. You can poke around with nodetool on the nodes themselves ( that uses JMX itself ) to get other metrics, but i have not been able to
get cache stats out of nodetool cfstats. I think it might be because they are no longer on the CF's mbean.
Interesting -- I completely overlooked the OS cache aspect, but how long does the OS keep cached pages? It seems they reside in memory for 4 hours at least (which happens to be the default time for key cache).. The CF has over 2.6 million
rows, and I am only fetching a random set of 5000 each time.
Where else can I examine the cache hit ratio? The nodes are remote servers behind some strict university controlled firewall, so it wouldn't be easy for me to tap in using JConsole. Thanks.