The Hadoop Distributed File System (HDFS) is a sub-project of the Apache Hadoop project. This Apache Software Foundation project is designed to provide a fault-tolerant file system designed to run on commodity hardware.
According to The Apache Software Foundation, the primary objective of HDFS is to store data reliably even in the presence of failures including NameNode failures, DataNode failures and network partitions. The NameNode is a single point of failure for the HDFS cluster and a DataNode stores data in the Hadoop file management system.
HDFS uses a master/slave architecture in which one device (the master) controls one or more other devices (the slaves). The HDFS cluster consists of a single NameNode and a master server manages the file system namespace and regulates access to files.
Also see Apache Hadoop.