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From Oren Benjamin <o...@clearspring.com>
Subject Re: Cassandra benchmarking on Rackspace Cloud
Date Mon, 19 Jul 2010 15:30:39 GMT
Certainly I'm using multiple cloud servers for the multiple client tests.  Whether or not they
are resident on the same physical machine, I just don't know.

   -- Oren

On Jul 18, 2010, at 11:35 PM, Brandon Williams wrote:

On Sun, Jul 18, 2010 at 8:45 PM, Oren Benjamin <oren@clearspring.com<mailto:oren@clearspring.com>>
wrote:
Thanks for the info.  Very helpful in validating what I've been seeing.  As for the scaling
limit...

>> The above was single node testing.  I'd expect to be able to add nodes and scale
throughput.  Unfortunately, I seem to be running into a cap of 21,000 reads/s regardless of
the number of nodes in the cluster.
>
> This is what I would expect if a single machine is handling all the
> Thrift requests.  Are you spreading the client connections to all the
> machines?

Yes - in all tests I add all nodes in the cluster to the --nodes list.  The client requests
are in fact being dispersed among all the nodes as evidenced by the intermittent TimedOutExceptions
in the log which show up against the various nodes in the input list.  Could it be a result
of all the virtual nodes being hosted on the same physical hardware?  Am I running into some
connection limit?  I don't see anything pegged in the JMX stats.

It's unclear if you're using multiple client machines for stress.py or not, a limitation of
24k/21k for a single quad-proc machine is normal in my experience.

-Brandon


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