I was trying to get some cluster wide statistics of the total insertions performed in my 3 node Cassandra 0.8.6 cluster. So I wrote a nice little program that gets the CompletedTasks attribute of org.apache.cassandra.db:type=Commitlog from every node, sums up the values and records them in a .csv every 10 sec or so. Everything works and I get my stats but later I found out that I am not really sure what this measure means. I think it is the individual column insertions performed! Am I correct?
In the meantime I installed the trial version of the DataStax Operations Center. The cluster wide dashboard, showing Writes performed as a function of time, gives me much smaller values of the rates, compared to the measurement I described before. The Datastax writes/sec are of the same order of magnitude as the batch writes I perform on the cluster. But somehow I cannot relate between this rate and the rate of my CompletedTasks measurement.
How do people usually measure insertion rates for their custers ? Per batch, per single columns or is actual data rate more important to know?