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  1. Hadoop HDFS
  2. HDFS-13157

Do Not Remove Blocks Sequentially During Decommission

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    Details

    • Type: Improvement
    • Status: Patch Available
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 3.0.0
    • Fix Version/s: None
    • Component/s: datanode, namenode
    • Labels:
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      Description

      From what I understand of DataNode decommissioning it appears that all the blocks are scheduled for removal in order.. I'm not 100% sure what the ordering is exactly, but I think it loops through each data volume and schedules each block to be replicated elsewhere. The net affect is that during a decommission, all of the DataNode transfer threads slam on a single volume until it is cleaned out. At which point, they all slam on the next volume, etc.

      Please randomize the block list so that there is a more even distribution across all volumes when decommissioning a node.

        Attachments

        1. HDFS-13157.1.patch
          7 kB
          David Mollitor

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              • Assignee:
                belugabehr David Mollitor
                Reporter:
                belugabehr David Mollitor
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                Dates

                • Created:
                  Updated: