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From aaron morton <aa...@thelastpickle.com>
Subject Re: Consistency Level throughput
Date Sun, 29 May 2011 10:22:23 GMT
You've not talked about how you are doing the tests (or i missed it). 

With 6 nodes and RF 3 when you read at ONE there is a 50% chance of the data read been served
locally. In which case the request will return to the client very quickly. Allowing X number
of clients to make Y number of requests. 

At the higher CL levels the latency of the requests is higher, so X clients cannot make Y
number of requests. 

The throughput of a client may change at different CL levels as it is making a single request
at a time. In general there is little impact on the throughput for the cluster as a whole.
 

How were you measuring the throughput? How many clients are you running ?

Cheers


On 27 May 2011, at 16:35, Ryu Kobayashi wrote:

> My question is my throughput per case.
> 
>> In general, cluster throughput = single node throughput * number of
>> nodes / replication factor.
> 
> Yes, I think so too.
> But I really want to ask is there are no results.
> 
> Could you look at the chart I made it?
> 
> http://goo.gl/mACQa
> 
> 
> 2011/5/27 Maki Watanabe <watanabe.maki@gmail.com>:
>> I assume your question is on that "how CL will affects on the throughput".
>> 
>> In theory, I believe CL will not affect on the throughput of the
>> Cassandra system.
>> In any CL, the coordinator node needs to submit write/read requests
>> along the RF specified for the KS.
>> But for the latency, CL will affects on.  Stronger CL will cause larger latency.
>> In the real world, it will depends on system configuration,
>> application design, data, and all of the environment.
>> However if you found shorter latency with stronger CL, there must be
>> some reason to explain the behavior.
>> 
>> maki
>> 
>> 2011/5/27 Ryu Kobayashi <beter.max@gmail.com>:
>>> Hi,
>>> 
>>> Question of Consistency Level throughput.
>>> 
>>> Environment:
>>> 6 nodes. Replication factor is 3.
>>> 
>>> ONE and QUORUM it was not for the throughput difference.
>>> ALL just extremely slow.
>>> Not ONE had only half the throughput.
>>> ONE, TWO and THREE were similar results.
>>> 
>>> Is there any difference between 2 nodes and 3 nodes?
>>> 
>>> --
>>>  <beter.max@gmail.com>
>>> twitter:@ryu_kobayashi
>>> 
>> 
>> 
>> 
>> --
>> w3m
>> 
> 
> 
> 
> -- 
>  <beter.max@gmail.com>
> twitter:@ryu_kobayashi


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