Edit the configuration files and execute commands on the NameNode host machine.
On the NameNode host machine, edit the
<HADOOP_CONF_DIR>/dfs.excludefile and add the list of DataNodes hostnames (separated by a newline character).
<HADOOP_CONF_DIR>is the directory for storing the Hadoop configuration files. For example,
Update the NameNode with the new set of excluded DataNodes. On the NameNode host machine, execute the following command:
su <HDFS_USER> hdfs dfsadmin -refreshNodes
<HDFS_USER>is the user owning the HDFS services. For example,
Open the NameNode web UI (
http://<NameNode_FQDN>:50070) and navigate to the DataNodes page. Check to see whether the state has changed to Decommission In Progress for the DataNodes being decommissioned.
When all the DataNodes report their state as Decommissioned (on the DataNodes page, or on the Decommissioned Nodes page at
http://<NameNode_FQDN>:8088/cluster/ nodes/decommissioned), all of the blocks have been replicated. You can then shut down the decommissioned nodes.
If your cluster utilizes a
dfs.includefile, remove the decommissioned nodes from the
<HADOOP_CONF_DIR>/dfs.includefile on the NameNode host machine, then execute the following command:
su <HDFS_USER> hdfs dfsadmin -refreshNodesNote
dfs.includefile is specified, all DataNodes are considered to be included in the cluster (unless excluded in the
hdfs-site.xmlare used to specify the