Details

    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.17.0
    • Component/s: None
    • Labels:
      None
    • Release Note:
      Change DFS block placement to allocate the first replica locally, the second off-rack, and the third intra-rack from the second.

      Description

      Currently, when writing out a block, dfs will place one copy to a local data node, one copy to a rack local node
      and another one to a remote node. This leads to a number of undesired properties:

      1. The block will be rack-local to two tacks instead of three, reducing the advantage of rack locality based scheduling by 1/3.

      2. The Blocks of a file (especiallya large file) are unevenly distributed over the nodes: One third will be on the local node, and two thirds on the nodes on the same rack. This may make some nodes full much faster than others,
      increasing the need of rebalancing. Furthermore, this also make some nodes become "hot spots" if those big
      files are popular and accessed by many applications.

      1. Trunk_Rack_Node_Mapping.jpg
        33 kB
        Lohit Vijayarenu
      2. Trunk_Block_Report.png
        30 kB
        Lohit Vijayarenu
      3. Patch2 Block Report.jpg
        56 kB
        Lohit Vijayarenu
      4. Patch2_Rack_Node_Mapping.jpg
        35 kB
        Lohit Vijayarenu
      5. Patch1_Rack_Node_Mapping.jpg
        34 kB
        Lohit Vijayarenu
      6. Patch1_Block_Report.png.jpg
        52 kB
        Lohit Vijayarenu
      7. HADOOP-2559-2.patch
        11 kB
        Lohit Vijayarenu
      8. HADOOP-2559-1-4.patch
        7 kB
        Lohit Vijayarenu
      9. HADOOP-2559-1-3.patch
        7 kB
        Lohit Vijayarenu
      10. HADOOP-2559-1-2.patch
        7 kB
        Lohit Vijayarenu
      11. HADOOP-2559-1.patch
        8 kB
        Lohit Vijayarenu
      12. HADOOP-2559-1.patch
        8 kB
        Lohit Vijayarenu

        Issue Links

          Activity

          Owen O'Malley made changes -
          Component/s dfs [ 12310710 ]
          Nigel Daley made changes -
          Status Resolved [ 5 ] Closed [ 6 ]
          Lohit Vijayarenu made changes -
          Release Note Change DFS block placement to allocate the first replica locally, the second off-rack, and the third intra-rack from the second.
          Description
          Currently, when writing out a block, dfs will place one copy to a local data node, one copy to a rack local node
          and another one to a remote node. This leads to a number of undesired properties:

          1. The block will be rack-local to two tacks instead of three, reducing the advantage of rack locality based scheduling by 1/3.

          2. The Blocks of a file (especiallya large file) are unevenly distributed over the nodes: One third will be on the local node, and two thirds on the nodes on the same rack. This may make some nodes full much faster than others,
          increasing the need of rebalancing. Furthermore, this also make some nodes become "hot spots" if those big
          files are popular and accessed by many applications.


          Currently, when writing out a block, dfs will place one copy to a local data node, one copy to a rack local node
          and another one to a remote node. This leads to a number of undesired properties:

          1. The block will be rack-local to two tacks instead of three, reducing the advantage of rack locality based scheduling by 1/3.

          2. The Blocks of a file (especiallya large file) are unevenly distributed over the nodes: One third will be on the local node, and two thirds on the nodes on the same rack. This may make some nodes full much faster than others,
          increasing the need of rebalancing. Furthermore, this also make some nodes become "hot spots" if those big
          files are popular and accessed by many applications.


          Chris Douglas made changes -
          Status Patch Available [ 10002 ] Resolved [ 5 ]
          Fix Version/s 0.17.0 [ 12312913 ]
          Resolution Fixed [ 1 ]
          Lohit Vijayarenu made changes -
          Status Open [ 1 ] Patch Available [ 10002 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-1-4.patch [ 12378053 ]
          Lohit Vijayarenu made changes -
          Status Patch Available [ 10002 ] Open [ 1 ]
          dhruba borthakur made changes -
          Link This issue is depended upon by HADOOP-2094 [ HADOOP-2094 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-1-3.patch [ 12377850 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-1-2.patch [ 12377849 ]
          Lohit Vijayarenu made changes -
          Status Open [ 1 ] Patch Available [ 10002 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-1.patch [ 12377544 ]
          Lohit Vijayarenu made changes -
          Attachment Patch2_Rack_Node_Mapping.jpg [ 12377157 ]
          Lohit Vijayarenu made changes -
          Attachment Patch1_Rack_Node_Mapping.jpg [ 12377156 ]
          Lohit Vijayarenu made changes -
          Attachment Trunk_Rack_Node_Mapping.jpg [ 12377155 ]
          Lohit Vijayarenu made changes -
          Attachment Patch2 Block Report.jpg [ 12377154 ]
          Lohit Vijayarenu made changes -
          Attachment Patch1_Block_Report.png.jpg [ 12377153 ]
          Lohit Vijayarenu made changes -
          Attachment Trunk_Block_Report.png [ 12377152 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-2.patch [ 12376211 ]
          Lohit Vijayarenu made changes -
          Attachment HADOOP-2559-1.patch [ 12376130 ]
          Robert Chansler made changes -
          Field Original Value New Value
          Assignee lohit vijayarenu [ lohit ]
          Runping Qi created issue -

            People

            • Assignee:
              Lohit Vijayarenu
              Reporter:
              Runping Qi
            • Votes:
              0 Vote for this issue
              Watchers:
              2 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:

                Development