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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HDFS-942) Read and write metrics misleading/not helpful
Date Tue, 02 Feb 2010 22:30:20 GMT

     [ https://issues.apache.org/jira/browse/HDFS-942?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Todd Lipcon updated HDFS-942:
-----------------------------

          Component/s: data-node
    Affects Version/s: 0.22.0

> Read and write metrics misleading/not helpful
> ---------------------------------------------
>
>                 Key: HDFS-942
>                 URL: https://issues.apache.org/jira/browse/HDFS-942
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: data-node
>    Affects Versions: 0.22.0
>            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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