Core Components of HDFS
There are three components of HDFS: 1. NameNode 2. Secondary NameNode 3. DataNode NameNode: NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNode (slave node). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients. I will be discussing this High Availability feature of Apache Hadoop HDFS in my next blog. The HDFS architecture is built in such a way that the user data never resides on the NameNode. The data resides on DataNode only. 1. NameNode is the centerpiece of HDFS. 2. NameNode is also known as the Master. 3. NameNode only stores the metadata of HDFS – the directory tree of all files in the file system, and tracks the files across the cluster. 4. NameNode does not store the actual data or the data set. The data itself is actually stored in the DataNode. 5. NameNode knows the list of the blocks and its location for any given file...