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  1. Hadoop HDFS
  2. HDFS-12272

chooseRemoteRack() semantics broken in trunk

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Critical
    • Resolution: Invalid
    • Affects Version/s: 3.0.0-alpha3
    • Fix Version/s: None
    • Component/s: block placement
    • Labels:
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      Description

      The chooseRemoteRack() method in the default block placement policy was designed to pick from maximum number of racks. E.g. If asked to pick 2 and there are 2 or more racks available, the two will be on different racks. It wasn't implicit or accidental semantics. There was a specific logic in chooseRandom() that makes it happen.

      This behavior is broken after HDFS-11530 as this logic was removed from chooseRandom(). Now the result is unpredictable. Sometimes the replicas end up in the same rack.

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              • Assignee:
                Unassigned
                Reporter:
                kihwal Kihwal Lee
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                • Created:
                  Updated:
                  Resolved: