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From Raghu Angadi <rang...@yahoo-inc.com>
Subject Re: [jira] Updated: (HADOOP-1180) NNbench test should be able to test the checksumfilesystem as well as the raw filesystem
Date Fri, 30 Mar 2007 00:19:24 GMT
hairong Kuang wrote:
> Two main reasons caused the performance decrease:
> 
> 1. NNBench sets the block size to be 1. Althouth it generates a file with
> only 1 byte,  but the file's checksum file has 16 bytes (12 bytes header
> plus 4 bytes checksums). Without the checksum file, only 1 block needs to be
> generated. With the checksum file, 17 blocks need to be generated. So the
> overhead of generating a checksum file is huge in this special case.
> Hadoop-1134 should help a lot for this.

thanks. The numbers now make sense.

Raghu.

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