@Michael Bronson The Namenode stores metadata about the data being stored in datanodes whereas the datanode stores the actual Data. The Namenode will also require RAM directly proportional to the number of data blocks in the cluster. A good rule of thumb is to assume 1GB of namenode memory for every 1 million blocks stored in the distributed file system. With 100 DataNodes in a cluster, 64GB of RAM on the namenode provides plenty of room to grow the cluster. So, thousands of datanodes can be handled by a single namenode, but there are many factors to consider: namenode memory size, number of blocks to be stored, block replication factor, how will the cluster be used, etc. In short, “number of datanodes a single name node can handle depends on the size of the name node (How much metadata it can hold)” Please accept the answer you found most useful ... View more

@Amit Mishra We can configure Knox with other authentication options too other than LDAP. Here is the link to the list of supported authentication providers for Knox (i.e., LDAP, PAM, Kerberos) https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.6.4/bk_security/content/authentication_providers.html https://knox.apache.org/books/knox-1-1-0/user-guide.html#HadoopAuth+Authentication+Provider Please accept the answer you found most useful ... View more