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From "Hiller, Dean" <>
Subject how to test our transfer speeds
Date Mon, 01 Apr 2013 17:31:08 GMT
(we plan on running similar performance tests on cassandra but wanted to understand the raw
foot print first)…..

Someone in ops was doing a test transferring 1T of data from one node to another.  I had a
huge concern I emailed him that this could end up being a completely sequential write not
testing random access speeds.  He has twenty 1T drives on each machine and I think he also
tried with one 1T drive seeing the same performance which makes sense if writing sequentially.
 Does anyone know of something that could generate a random access pattern such that we could
time that?  Right now, he was measuring 253MB / second from the time it took and the 1T of
data.  I would like to find the much worse case of course.

If not, maybe I just generate the same 1,000,000 files on each machine, then randomly delete
1/2 the files and stream them from the other machine as writing those files would all be in
random locations again forcing a much worse measurement of MB/sec I would think.



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