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Hadoop 2.x Administration Cookbook by Gurmukh Singh

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HDFS balancer

In a long-running cluster, there might be unequal distribution of data across Datanodes. This could be due to failures of nodes or the addition of nodes to the cluster.

To make sure that the data is equally distributed across Datanodes, it is important to use Hadoop balancer to redistribute the blocks.

Getting ready

For this recipe, you will again use the same node on which we have already configured Namenode.

All operations will be done by user hadoop.

How to do it...

  1. Log in the nn1.cluster1.com node and change to user hadoop.
  2. Execute the balancer command as shown in the following screenshot:
    How to do it...
  3. By default, the balancer threshold is set to 10%, ...

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