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From tienduc_dinh <tienduc_d...@yahoo.com>
Subject Re: TestDFSIO delivers bad values of "throughput" and "average IO rate"
Date Wed, 07 Jan 2009 20:46:57 GMT

hi Konstantin,

sorry for my mistake, it was not 5012, it was 512.

Of course, it is great that the throughput is mb/sec per client like you
said. In this case we have circa 120 MB/sec :clap:

But I'm not sure, if that really was. Please follow my example and
calculation of throughput

> hadoop-0.18.0/bin/hadoop jar testDFSIO.jar -write -fileSize 512 -nrFiles 4 

The value of throughput = 30,16

The information in /benchmarks/TestDFSIO/io_write/part-00000 is :

f:rate	121631.625
f:sqrate	3726004.8
l:size	2147483648
l:tasks	4
l:time	67900

To calculate throughput in source code:
throughput = size * 1000.0 / (time * MEGA),

So in this case we have throughput = 2147483648 * 1000 / (time * MEGA) =
2048 * 1000 / 67900 = 30,16.

Because the value of "size" is 2048 GB and not 512 MB, that's why I'm not
sure about it.

Can you give me a hint again, thanks lots.

Tien Duc Dinh

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