Is Namenode machine same as DataNode machine as in terms of hardware?
Unlike the DataNodes, a NameNode is a highly available server. That manages the File System Namespace and maintains the metadata information. Metadata information is a number of blocks, their location, replicas and other details. It also executes file system execution such as naming, closing, opening files/directories.
Therefore, NameNode requires higher RAM for storing the metadata for millions of files. Whereas, DataNode is responsible for storing actual data in HDFS. It performs read and write operation as per request of the clients. Therefore, Datanode needs to have a higher disk capacity for storing huge data sets.