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Posted to hdfs-dev@hadoop.apache.org by "ryan rawson (JIRA)" <ji...@apache.org> on 2010/02/02 23:28:18 UTC

[jira] Created: (HDFS-942) Read and write metrics misleading/not helpful

Read and write metrics misleading/not helpful
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                 Key: HDFS-942
                 URL: https://issues.apache.org/jira/browse/HDFS-942
             Project: Hadoop HDFS
          Issue Type: Bug
            Reporter: ryan rawson


the metrics wrap the entire readBlock() writeBlock() call (in DataXciever#run())

The problem with this is it includes the client socket read/write time. This means if a client is slow at streaming a write block (eg: in hbase) then it skews the write metrics and makes it look like the server is really slow.  Same problem with reads.

It would be nice if reads/writes meant actually local disk io and related processing (eg: checksum verification/generation)

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