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  1. Hadoop HDFS
  2. HDFS-6840

Clients are always sent to the same datanode when read is off rack

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Details

    • Bug
    • Status: Closed
    • Critical
    • Resolution: Fixed
    • 2.5.0
    • 2.6.0
    • None
    • None

    Description

      After HDFS-6268 the sorting order of block locations is deterministic for a given block and locality level (e.g.: local, rack. off-rack), so off-rack clients all see the same datanode for the same block. This leads to very poor behavior in distributed cache localization and other scenarios where many clients all want the same block data at approximately the same time. The one datanode is crushed by the load while the other replicas only handle local and rack-local requests.

      Attachments

        1. hdfs-6840.branch-2.patch
          28 kB
          Andrew Wang
        2. hdfs-6840.003.patch
          19 kB
          Andrew Wang
        3. hdfs-6840.002.patch
          19 kB
          Andrew Wang
        4. hdfs-6840.001.patch
          18 kB
          Andrew Wang

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. HDFS-4253 block replica reads get hot-spots due to NetworkTopology#pseudoSortByDistance

          • Major - Major loss of function.
          • Resolved
          is broken by

          Improvement - An improvement or enhancement to an existing feature or task. HDFS-6268 Better sorting in NetworkTopology#pseudoSortByDistance when no local node is found

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Closed
          relates to

          Improvement - An improvement or enhancement to an existing feature or task. HADOOP-11107 Improve tests to not rely on JDK random implementation

          • Major - Major loss of function.
          • Open

          Improvement - An improvement or enhancement to an existing feature or task. HDFS-6701 Make seed optional in NetworkTopology#sortByDistance

          • Major - Major loss of function.
          • Closed

          Activity

            People

              andrew.wang Andrew Wang
              jlowe Jason Darrell Lowe
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              Dates

                Created:
                Updated:
                Resolved: