[HDFS-8418] Fix the isNeededReplication calculation for Striped block in NN

• Type: Sub-task
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: HDFS-7285
• Hadoop Flags: Reviewed
• Assignee: Yi Liu
• Reporter: Yi Liu
• Created: 18/May/15 05:22
• Updated: 30/Sep/15 19:38
• Resolved: 19/May/15 02:08

Description

Currently when calculating isNeededReplication for striped block, we use BlockCollection#getPreferredBlockReplication to get expected replica number for striped block. See an example:

public void checkReplication(BlockCollection bc) {
    final short expected = bc.getPreferredBlockReplication();
    for (BlockInfo block : bc.getBlocks()) {
      final NumberReplicas n = countNodes(block);
      if (isNeededReplication(block, expected, n.liveReplicas())) { 
        neededReplications.add(block, n.liveReplicas(),
            n.decommissionedAndDecommissioning(), expected);
      } else if (n.liveReplicas() > expected) {
        processOverReplicatedBlock(block, expected, null, null);
      }
    }
  }

But actually it's not correct, for example, if the length of striped file is less than a cell, then the expected replica of the block should be 1 + parityBlkNum instead of dataBlkNum + parityBlkNum.