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From Alexandru Dan Sicoe <>
Subject CompletedTasks attribute exposed via JMX
Date Tue, 11 Oct 2011 14:44:10 GMT
Hello everyone,
 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
 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

How do people usually measure insertion rates for their custers ? Per batch,
per single columns or is actual data rate more important to know?


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