HDFS is a Distributed File Storage system in which we write data and then read that same data. NameNode is a master node that contains metadata information about all the files and DataNode space. The DataNode is a worker node that stores real files. Every read and write request will go through NameNode. HDFS is known for the write once read many pattern, meaning that the file is written in HDFS only once and can be read many times. Files stored in HDFS are not editable but appending new data to a file is allowed.
In this section, we will cover the internals of HDFS read and write operations, and will see how clients communicate with NameNode and DataNode for read/write operations.
