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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-7497) Inconsistent report of decommissioning DataNodes between dfsadmin and NameNode webui
Date Tue, 09 Dec 2014 05:21:13 GMT
Yongjun Zhang created HDFS-7497:
-----------------------------------

             Summary: Inconsistent report of decommissioning DataNodes between dfsadmin and
NameNode webui
                 Key: HDFS-7497
                 URL: https://issues.apache.org/jira/browse/HDFS-7497
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: datanode, namenode
            Reporter: Yongjun Zhang
            Assignee: Yongjun Zhang


It's observed that dfsadmin report list DNs in the decomm state while NN UI list DNs in dead
state.

I found what happens is:

NN webui uses two steps to get the result:

* first collect a list of all alive DNs, 
* traverse through all live  DNs to find decommissioning DNs. 

It calls the following method to decide whether a DN is dead or alive:
{code}
  /** Is the datanode dead? */
  boolean isDatanodeDead(DatanodeDescriptor node) {
    return (node.getLastUpdate() <
            (Time.now() - heartbeatExpireInterval));
  }
{code}

On the other hand, dfsadmin traverse all DNs to find to all decommissioning DNs (check whether
a DN is in {{AdminStates.DECOMMISSION_INPROGRESS}} state), without checking whether a DN is
dead or alive like above.

The problem is, when a DN is determined to be dead, its state may still be {{AdminStates.DECOMMISSION_INPROGRESS}}
.










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