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From Code Box <>
Subject Cassandra Evaluation/ Benchmarking: Throughput not scaling as expected neither latency showing good numbers
Date Tue, 17 Jul 2012 04:13:11 GMT
I am doing Cassandra Benchmarking using YCSB for evaluating the best
performance for my application which will be both read and write intensive.
I have set up a three cluster environment on EC2 and i am using YCSB in the
same availability region as a client. I have tried various combinations of
tuning cassandra parameters like FSync ( Setting to batch and periodic ),
Increasing the number of rpc_threads, increasing number of concurrent reads
and concurrent writes, write consistency one and Quorum i am not getting
very great results and also i do not see a linear graph in terms of
scalability that is if i increase the number of clients i do not see an
increase in the throughput.

Here are some sample numbers that i got :-

*Test 1:-  Write Consistency set to Quorum Write Proportion = 100%. FSync =
Batch and Window = 0ms*

ThreadsThroughput ( write per sec )Avg Latency (ms)TP95(ms)TP99(ms)Min(ms)

1021493.198451.499291  100407023.828702.2260   200415145.96571301.71242

If you look at the numbers the number of threads do not increase the
throughput. Also the latency values are not that great. I am using fsync
set to batch and with 0 ms window.

*Test 2:- ** Write Consistency set to Quorum Write Proportion = 100%. FSync
= Periodic and Window = 1000 ms*
Are these numbers expected numbers or does Cassandra perform better ? Am i
missing something ?

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