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From onmstester onmstester <>
Subject RE: yet another benchmark bottleneck
Date Mon, 12 Mar 2018 10:37:37 GMT
1.2 TB 15K

latency reported by stress tool is 7.6 ms. disk latency is 2.6 ms

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---- On Mon, 12 Mar 2018 14:02:29 +0330 Jacques-Henri Berthemet &lt;;
wrote ----

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 &lt;;

 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 &lt;;
wrote ----



Yes, i'm dosing a single host test


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---- On Mon, 12 Mar 2018 09:24:04 +0330 Jeff Jirsa &lt;; 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 &lt;;



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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