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  1. Hadoop HDFS
  2. HDFS-15495

Decommissioning a DataNode with corrupted EC files should not be blocked indefinitely



    • Improvement
    • Status: Open
    • Major
    • Resolution: Unresolved
    • 3.0.0
    • None
    • block placement, ec
    • None


      Originally discovered in patched CDH 6.2.1 (with a bunch of EC fixes: HDFS-14699, HDFS-14849, HDFS-14847, HDFS-14920, HDFS-14768, HDFS-14946, HDFS-15186).

      When there's an EC file marked as corrupted on NN, if the admin tries to decommission a DataNode having one of the remaining blocks of the corrupted EC file, the decom will never finish unless the file is recovered by putting the missing blocks back in:

      The endless DatanodeAdminManager check loop, every 30s
      2020-07-23 16:36:12,805 TRACE blockmanagement.DatanodeAdminManager: Processed 0 blocks so far this tick
      2020-07-23 16:36:12,806 DEBUG blockmanagement.DatanodeAdminManager: Processing Decommission In Progress node
      2020-07-23 16:36:12,806 TRACE blockmanagement.DatanodeAdminManager: Block blk_-9223372036854775728_1013 numExpected=9, numLive=4
      2020-07-23 16:36:12,806 INFO BlockStateChange: Block: blk_-9223372036854775728_1013, Expected Replicas: 9, live replicas: 4, corrupt replicas: 0, decommissioned replicas: 0, decommissioning replicas: 1, maintenance replicas: 0, live entering maintenance replicas: 0, excess replicas: 0, Is Open File: false, Datanodes having this block: , Current Datanode:, Is current datanode decommissioning: true, Is current datanode entering maintenance: false
      2020-07-23 16:36:12,806 DEBUG blockmanagement.DatanodeAdminManager: Node still has 1 blocks to replicate before it is a candidate to finish Decommission In Progress.
      2020-07-23 16:36:12,806 INFO blockmanagement.DatanodeAdminManager: Checked 1 blocks and 1 nodes this tick

      "Corrupted" file here meaning the EC file doesn't have enough EC blocks in the block group to be reconstructed. e.g. for RS-6-3-1024k, when there are less than 6 blocks for an EC file, the file can no longer be retrieved correctly.




            smeng Siyao Meng
            smeng Siyao Meng
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