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From "Alejandro Abdelnur (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5946) Webhdfs DN choosing code is flawed
Date Thu, 13 Feb 2014 20:03:25 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5946?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13900678#comment-13900678

Alejandro Abdelnur commented on HDFS-5946:

You get data locality only for the first block of the file, for subsequent blocks you are
stuck to the DN serving the file via webhdfs.

> Webhdfs DN choosing code is flawed
> ----------------------------------
>                 Key: HDFS-5946
>                 URL: https://issues.apache.org/jira/browse/HDFS-5946
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode, webhdfs
>    Affects Versions: 3.0.0, 2.4.0
>            Reporter: Daryn Sharp
>            Priority: Critical
> HDFS-5891 improved the performance of redirecting webhdfs clients to a DN.  Instead of
attempting a connection with a 1-minute timeout, the NN skips decommissioned nodes.
> The logic appears flawed.  It finds the index of the first decommissioned node, if any,
> * Throws an exception if index = 0, even if other nodes later in the list are not decommissioned.
> * Else picks a random node prior to the index.  Let's say there are 10 replicas, 2nd
location is decommissioned.  All clients will be redirected to the first location even though
there are 8 other valid locations.

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