The Balancer tool available in Hadoop is used to balance the data blocks across all the datanodes when a new datanode is added or when an existing datanode reaches full capacity.
Before you can rebalance a cluster, we need to add the balancer service. The following are the steps to add the Balancer service:
- Navigate to the Clusters menu and select HDFS.
- Click on the Instances tab and select Add to bring up the Customize Role Assignments screen as shown in the following screenshot:
- Click on Select a host for the Balancer section to bring up the host selection screen as shown in the following screenshot. Select a host and click on OK. Here I have selected node4.
- In the next screen, click on Continue. You should now see the Balancer service added, as shown in the following screenshot:
Once the Balancer service is installed successfully, you can perform the rebalancing operation. The following are the steps to perform the rebalancing operation from Cloudera Manager:
- Navigate to the Clusters menu and select HDFS.
- Navigate to the Instances tab and click on the Balancer service from the list of services to navigate to the balancer screen as shown in the following screenshot:
- Click on the Actions button and click on Rebalance as shown in the following screenshot:
- You will be asked to confirm the action as shown in the following screenshot:
- Click on Rebalance to start the rebalancing operation. On successful completion, the data blocks should be balanced across the datanodes on the cluster and you should see a message like the one shown in the following screenshot:
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.