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From Jabbar <>
Subject Uneven CPU load on a 4 node cluster
Date Tue, 29 Jan 2013 16:29:17 GMT

I've been testing a four identical node cassanda 1.2 cluster for a number
of days. I have written a c# client using cassandra sharp() which inserts
data into a table.

The keyspace difinition is

 WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'dc1' : 3};

The table definition is

CREATE TABLE datapoints (
 siteid bigint,
 time timestamp,
 channel int,
 data float,
 PRIMARY KEY ((siteid, channel),time)

I am finding that the CPU load on one of the servers stays at ~90% whilst
the load on the other servers stays < 40%. All the servers are supposed to
be identical.

The client library I  am using does load balancing between all nodes.

I have also used the cassandra stress tool as follows

cassandra-stress -d,,,
--replication-factor 3 -n 10000000 -t 100

and have found that  it behaves similarly.

Can somebody explain why this happens?


 A Jabbar Azam

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