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From Roger Warner <rwar...@pandora.com>
Subject Reversed read write performance.
Date Fri, 14 Jul 2017 21:11:31 GMT
I’m confused about read vs write performance.   I was expecting to see higher write than
read perf.   I’m seeing the opposite by nearly 2X
Please help.  Am I doing/configuring something wrong or do I have the wrong expectations.
  I am very new to Cassandra.   And this is not using Datastax. .

I have a new cluster I’m trying to estimate capacity of.

·         6 nodes, 2 datacenters, 3:3  – but on the same physical network as of now

·         500G SATA SSD drives benched at 250MB/s on these machines

·         32 core,  2Ghz, 60G of RAM / node

·         Cassandra 3.11

Cassandra-stress being run on the same build as these.

·         Cl=LOCAL_ONE

·         Mixed test 4:1

·         Defaults otherwise

·         Testing  using –nodes from dci.

Schema

·         Tweaked Cassandra-stress schema

·         NetworkToplogyStragety

·         2 DC

·         3 replicas

·         SizeTieredCompactionStrategy



I’ve run 4:1 read to write I see ~325Kops/s
I see about write to read I see ~150Kops/s

Any suggestions a very much appreciated.
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