HDFS (Hadoop Distributed File System) is the storage unit of Hadoop. It is responsible for storing different kinds of data as blocks in a distributed environment. It follows master and slave topology.
* NameNode : NameNode is the master node in the distributed environment and it maintains the metadata information for the blocks of data stored in HDFS like block location, replication factors etc.
* DataNode : DataNodes are the slave nodes, which are responsible for storing data in the HDFS. NameNode manages all the DataNodes.
YARN (Yet Another Resource Negotiator) is the processing framework in Hadoop, which manages resources and provides an execution environment to the processes.
* ResourceManager : It receives the processing requests, and then passes the parts of requests to corresponding NodeManagers accordingly, where the actual processing takes place. It allocates resources to applications based on the needs.
* NodeManager : NodeManager is installed on every DataNode and it is responsible for the execution of the task on every single DataNode.
