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From Peter Schuller <>
Subject Re: performance degradation in cluster
Date Thu, 03 Feb 2011 08:16:15 GMT
> First time I tun single instance of Cassandra and my application on a system
> (16GB ram and 8 core), the time taken was 480sec.
> When I added one more system ,(means this time I was running 2 instance
> of Cassandra in cluster) and running application from single client , I
> found time taken in increased to 1000sec.   And I also found that that data
> distribution was also very odd on both system (in one system data were about
> 2.5GB and another were 140MB).
> Is any configuration require while running Cassandra in a cluster other than
> adding seeds ?

For starters:

(1) Are you spreading your data around evenly across row? Rows
determine where data is placed in the cluster.
(2) Is your ring actually balanced? (nodetool ring, they should have 50/50)
(3) Is your test concurrent/multi-threaded? Increasing total time
would be expected if you're moving from local traffic only to running
against remote machines,  if your test is a sequential workload.
Adding machines increases aggregate throughput across multiple
clients; it won't make individual requests faster (except indirectly
of course by avoiding overloaded conditions).

/ Peter Schuller

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