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From Chris Marino <ch...@vcider.com>
Subject Different Load values after stress test runs....
Date Tue, 23 Aug 2011 15:57:52 GMT
Hi, we're running some performance tests against some clusters and I'm
curious about some of the numbers I see.

I'm running the stress test against two identically configured clusters, but
after I run at stress test, I get different Load values across the
clusters?

The difference between the two clusters is that one uses standard EC2
interfaces, but the other runs on a virtual network. Are these differences
indicating something that I should be aware of??

Here is a sample of the kinds of results I'm seeing.

Address         DC          Rack        Status State   Load            Owns
   Token

                                 12760588759xxx
10.0.0.17       DC1         RAC1        Up     Normal  94 MB
25.00%  0
10.0.0.18       DC1         RAC1        Up     Normal  104.52 MB
25.00%  42535295865xxx
10.0.0.19       DC1         RAC1        Up     Normal  78.58 MB
 25.00%  85070591730xxx
10.0.0.20       DC1         RAC1        Up     Normal  78.58 MB
 25.00%  12760588759xxx

Address         DC          Rack        Status State   Load            Owns
   Token

                                    12760588759xxx
10.120.35.52    DC1         RAC1        Up     Normal  103.74 MB
25.00%  0
10.120.6.124    DC1         RAC1        Up     Normal  118.99 MB
25.00%  42535295865xxx
10.127.90.142   DC1         RAC1        Up     Normal  104.26 MB
25.00%  85070591730xxx
10.94.69.237    DC1         RAC1        Up     Normal  75.74 MB
 25.00%  12760588759xxx

The first cluster with the vNet (10.0.0.0/28 addresses) consistently show
smaller Load values. The total Load of 355MB vs. 402MB with native EC2
interfaces?? Is a total Load value even meaningful?? The stress test is the
very first thing that's run against the clusters.

[I'm also a little puzzled that these numbers are not uniform within the
clusters, but I suspect that's because the stress test is using a key
distribution that is Gaussian.  I'm not 100% sure of this either since I've
seen conflicting documentation. Haven't tried 'random' keys, but I presume
that would change them to be uniform]

Except for these curious Load numbers, things seem to be running just fine.
Getting good fast results. Over 10 iterations I'm getting more than 10-12K
inserts per sec. (default values for the stress test).

Should I expect the Load to be the same across different clusters?? What
might explain the differences I'm seeing???

Thanks in advance.
CM

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