I mentioned that already tested increasing client threads + many stress-client 
instances in one node + two stress-client in two separate nodes, in all of them 
the sum of throughputs is less than 130K. I've been tuning all aspects of OS 
and Cassandra (whatever I've seen in config files!) for two days, still no luck!


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---- On Mon, 12 Mar 2018 16:38:22 +0330 Jacques-Henri Berthemet 
<jacques-henri.berthe...@genesys.com> wrote ----




What happens if you increase number of client threads?

Can you add another instance of cassandra-stress on another host?

 

--

Jacques-Henri Berthemet


 

From: onmstester onmstester [mailto:onmstes...@zoho.com] 

 Sent: Monday, March 12, 2018 12:50 PM

 To: user <user@cassandra.apache.org>

 Subject: RE: yet another benchmark bottleneck




 

no luck even with 320 threads for write


 


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---- On Mon, 12 Mar 2018 14:44:15 +0330 Jacques-Henri Berthemet 
<jacques-henri.berthe...@genesys.com> wrote ----



 


It makes more sense now, 130K is not that bad.

 

According to cassandra.yaml you should be able to increase your number of write 
threads in Cassandra:

# On the other hand, since writes are almost never IO bound, the ideal

# number of "concurrent_writes" is dependent on the number of cores in

# your system; (8 * number_of_cores) is a good rule of thumb.

concurrent_reads: 32

concurrent_writes: 32

concurrent_counter_writes: 32

 

Jumping directly to 160 would be a bit high with spinning disks, maybe start 
with 64 just to see if it gets better.

 

--

Jacques-Henri Berthemet


 

From: onmstester onmstester [mailto:onmstes...@zoho.com]


Sent: Monday, March 12, 2018 12:08 PM


To: user <user@cassandra.apache.org>


Subject: RE: yet another benchmark bottleneck




 

RF=1


No errors or warnings.


Actually its 300 Mbit/seconds and 130K OP/seconds. I missed a 'K' in first 
mail, but anyway! the point is: More than half of node resources (cpu, mem, 
disk, network) is unused and i can't increase write throughput.


 


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---- On Mon, 12 Mar 2018 14:25:12 +0330 Jacques-Henri Berthemet 
<jacques-henri.berthe...@genesys.com> wrote ----



 


Any errors/warning in Cassandra logs? What’s your RF?

Using 300MB/s of network bandwidth for only 130 op/s looks very high.

 

--

Jacques-Henri Berthemet


 

From: onmstester onmstester [mailto:onmstes...@zoho.com]


Sent: Monday, March 12, 2018 11:38 AM


To: user <user@cassandra.apache.org>


Subject: RE: yet another benchmark bottleneck




 

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 
<jacques-henri.berthe...@genesys.com> wrote ----



 


What’s your disk latency? What kind of disk is it?

 

--

Jacques-Henri Berthemet


 

From: onmstester onmstester [mailto:onmstes...@zoho.com]


Sent: Monday, March 12, 2018 10:48 AM


To: user <user@cassandra.apache.org>


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 
<onmstes...@zoho.com> wrote ----



 


Apache-cassandra-3.11.1


Yes, i'm dosing a single host test


 


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---- On Mon, 12 Mar 2018 09:24:04 +0330 Jeff Jirsa <jji...@gmail.com> 
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 
<onmstes...@zoho.com> wrote:


 





 


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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