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.
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
.
Log in the nn1.cluster1.com node and change to user
hadoop
.Execute the balancer command as shown in the following screenshot:
By default, the balancer threshold is set to 10%, but we can change it, as shown in the following screenshot: