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The following page has been changed by LohitVijayarenu: http://wiki.apache.org/hadoop/FAQ ------------------------------------------------------------------------------ Hadoop offers the ''decommission'' feature to retire a set of existing data-nodes. The nodes to be retired should be included into the ''exclude file'', and the exclude file name should be specified as a configuration parameter - [http://hadoop.apache.org/core/docs/current/hadoop-default.html#dfs.hosts.exclude dfs.hosts.exclude]. + [http://hadoop.apache.org/core/docs/current/hadoop-default.html#dfs.hosts.exclude dfs.hosts.exclude]. This file should have been specified during namenode startup. It could be a zero length file. Then the shell command {{{ bin/hadoop dfsadmin -refreshNodes }}} - should be called, which forces the name-node to re-read its configuration files, including the exclude file + should be called, which forces the name-node to re-read the exclude file and start the decommission process. The nodes can be removed whenever decommission is finished. Decommission does not happen momentarily since we do not want the cluster to be overwhelmed with just this one job.
