[jira] Created: (HDFS-694) Add a test to make sure that node decomission does not get blocked by underreplicated blocks in an unclosed file

["Hairong Kuang (JIRA)" <ji...@apache.org>]

Add a test to make sure that node decomission does not get blocked by underreplicated blocks in an unclosed file
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                 Key: HDFS-694
                 URL: https://issues.apache.org/jira/browse/HDFS-694
             Project: Hadoop HDFS
          Issue Type: Test
    Affects Versions: 0.21.0
            Reporter: Hairong Kuang
             Fix For: 0.21.0


We have a cluster that took  much longer time to decommission datanodes than usual. It turned out to be caused by an open file. In HDFS 0.20 when a file is open, NN does not schedule any block belonged to this file to replicate. So if an open file has an under-replicated block with a replica on a decommission datanode, the decommission won't complete until the file is closed.

The new append implementation changed the replication strategy that any complete block in an unclosed file will be scheduled to be replicated if it becomes under-replicated. This jira aims to add a test to make sure that node decommission does not get blocked by under-replicated blocks in an open file.

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