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I want to remove nodes from my cluster gracefully. I added the following to my hadoop-site.xml:


I'm adding a node to be removed to the file and executing

hadoop dfsadmin -refreshNodes

as root, but I get

refreshNodes: org.apache.hadoop.fs.permission.AccessControlException: Superuser privilege is required

The mod on the HDFS partition is 777.

Running Cloudera's hadoop-ec2 distribution, ver 0.18

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2 Answers 2

up vote 1 down vote accepted

have a look in ${HADOOP_CONF_DIR}/hadoop-policy.xml and see if the root has permissions to do that, root maybe superuser over the system, however may not be over the app.

Try thi link


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The property dfs.hosts.exclude names a file that contains a list of hosts that are not permitted to connect to the namenode. The full pathname of the file must be specified.

cd <hadoop_installation>/bin

  • To start datanode start datanode

  • To start tasktracker start tasktracker

  • To stop datanode (remove the datanode from the cluster) stop datanode

  • To stop tasktracker (remove tasktracker from the cluster) stop tasktracker

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