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From Jacques-Henri Berthemet <>
Subject RE: yet another benchmark bottleneck
Date Mon, 12 Mar 2018 10:32:29 GMT
What’s your disk latency? What kind of disk is it?

Jacques-Henri Berthemet

From: onmstester onmstester []
Sent: Monday, March 12, 2018 10:48 AM
To: user <>
Subject: Re: yet another benchmark bottleneck

Running two instance of Apache Cassandra on same server, each having their own commit log
disk dis not help. Sum of cpu/ram usage  for both instances would be less than half of all
available resources. disk usage is less than 20% and network is still less than 300Mb in Rx.

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---- On Mon, 12 Mar 2018 09:34:26 +0330 onmstester onmstester <<>>
wrote ----

Yes, i'm dosing a single host test

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---- On Mon, 12 Mar 2018 09:24:04 +0330 Jeff Jirsa <<>>
wrote ----

Would help to know your version. 130 ops/second sounds like a ridiculously low rate. Are you
doing a single host test?

On Sun, Mar 11, 2018 at 10:44 PM, onmstester onmstester <<>>

I'm going to benchmark Cassandra's write throughput on a node with following spec:

  *   CPU: 20 Cores
  *   Memory: 128 GB (32 GB as Cassandra heap)
  *   Disk: 3 seprate disk for OS, data and commitlog
  *   Network: 10 Gb (test it with iperf)
  *   Os: Ubuntu 16

Running Cassandra-stress:
cassandra-stress write n=1000000 -rate threads=1000 -mode native cql3 -node X.X.X.X

from two node with same spec as above, i can not get throughput more than 130 Op/s. The clients
are using less than 50% of CPU, Cassandra node uses:

  *   60% of cpu
  *   30% of memory
  *   30-40% util in iostat of commitlog
  *   300 Mb of network bandwidth
I suspect the network, cause no matter how many clients i run, cassandra always using less
than 300 Mb. I've done all the tuning mentioned by datastax.
Increasing wmem_max and rmem_max did not help either.

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