To determine if you can finalize the upgrade, run important workloads and ensure that they are successful. After you have finalized the upgrade, you cannot roll back to a previous version of HDFS without using backups.Verifying that you are ready to finalize the upgrade can take a long time. Make sure you have enough free disk space, keeping in mind that the following behavior continues until the upgrade is finalized: Deleting files does not free up disk space. Using the balancer causes all moved replicas to be duplicated. All on-disk data representing the NameNodes metadata is retained, which could more than double the amount of space required on the NameNode and JournalNode disks. Go to the HDFS service. Click the Instances tab. Click the link for the NameNode instance.The NameNode instance page displays. Select Actions > Finalize Metadata Upgrade and click Finalize Metadata Upgrade to confirm.