Using ViewFs to manage multiple namespaces
View File System (ViewFs) helps you manage clusters with multiple NameNodes; and therefore, multiple namespaces, in an HDFS federation.
ViewFs is analogous to client side mount tables in UNIX or Linux systems. You can use ViewFs to create personalized namespace views and cluster-specific common views for file and directory paths corresponding to locations on different NameNodes of the cluster. You can create a cluster-specific global namespace such that applications behave the same way in a federation as they would in a cluster without support for federated NameNodes.
For information about using Ambari to configure ViewFs, see Configure ViewFs in the Ambari documentation.