Benefits of an HDFS Federation
HDFS federation provides namespace scalability, performance advantage because of scaling read/write throughput, and isolation of applications and users in a multitenanted environment.
Namespace Scalability: Federation adds namespace horizontal scaling. Large deployments or deployments using lot of small files benefit from namespace scaling by allowing more NameNodes to be added to the cluster.
Performance: File system throughput is not limited by a single NameNode. Adding more NameNodes to the cluster scales the file system read/write throughput.
Isolation: A single NameNode does not offer namespace isolation in a multi-user environment. By using multiple NameNodes, different categories of applications and users can be isolated to different namespaces.