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From Jonathan Ellis <>
Subject Re: Cassandra benchmarking on Rackspace Cloud
Date Mon, 19 Jul 2010 21:18:15 GMT
Now keep adding clients until it stops making the numbers go up...

On Mon, Jul 19, 2010 at 2:51 PM, David Schoonover
<> wrote:
> Sorry, mixed signals in my response. I was partially replying to suggestions that we
were limited by the box's NIC or DC's bandwidth (which is gigabit, no dice there). I also
ran the tests with -t50 on multiple tester machines in the cloud with no change in performance;
I've now rerun those tests on dedicated hardware.
>        reads/sec @
> nodes   one client      two clients
> 1       53k             73k
> 2       37k             50k
> 4       37k             50k
> Notes:
> - All notes from the previous dataset apply here.
> - All clients were reading with 50 processes.
> - Test clients were not co-located with the databases or each other.
> - All machines are in the same DC.
> - Servers showed about 20MB/sec in network i/o for the multi-node clusters, which is
well under the max for gigabit.
> - Latency was about 2.5ms/req.
> At this point, we'd really appreciate it if anyone else could attempt to replicate our
results. Ultimately, our goal is to see an increase in throughput given an increase in cluster
> --
> David Schoonover
> On Jul 19, 2010, at 2:25 PM, Stu Hood wrote:
>> If you put 25 processes on each of the 2 machines, all you are testing is how fast
50 processes can hit Cassandra... the point of using more machines is that you can use more
>> Presumably, for a single machine, there is some limit (K) to the number of processes
that will give you additional gains: above that point, you should use more machines, each
running K processes.

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support

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