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From pob <peterob...@gmail.com>
Subject writes performance
Date Sun, 20 Mar 2011 02:34:12 GMT
Hello,

I set up cluster with 3 nodes/ 4Gram,4cores,raid0. I did experiment with
stress.py to see how fast my inserts are. The results are confusing.

In each case stress.py was inserting 170KB of data:
1)
stress.py was inserting directly to one node -dNode1, RF=3, CL.ONE

300000 inserts in 1296 sec (300000,246,246,0.01123401983,1296)

2)
stress.py was inserting directly to one node -dNode1, RF=3, CL.QUORUM

300000 inserts in 987 sec   (300000,128,128,0.00894131883979,978)

3)
stress.py was inserting random into all 3 nodes  -dNode1,Node2,Node3 RF=3,
CL.QUORUM

300000 inserts in 784 sec (300000,157,157,0.00900169542641,784)

4)
stress.py was inserting directly to one node -dNode1, RF=3, CL.ALL

similar to case 1)
-------

Im not surprising about cases 2,3) but the biggest surprise for me is why
cl.one is slower then cl.quorum. CL.one has less "acks", shorter time of
waiting... and so on.

I was looking at some blogs about "write" architecture but the reason is
still not clear for me.

http://www.mikeperham.com/2010/03/13/cassandra-internals-writing/
http://prettyprint.me/2010/05/02/understanding-cassandra-code-base/


Thanks for advice.


Best,
Peter

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