The Apache Hadoop project develops open-source software for reliable, scalable, distributed computing. The Apache Hadoop software library is a framework that allows for the distributed processing of large data sets across clusters of computers using simple programming models. It is designed to scale up from single servers to thousands of machines, each offering local computation and storage. Rather than rely on hardware to deliver high-availability, the library itself is designed to detect and handle failures at the application layer, so delivering a highly-available service on top of a cluster of computers, each of which may be prone to failures.

The project includes these modules :

• Hadoop Common : The common utilities that support the other Hadoop modules.
• Hadoop Distributed File System (HDFS™) : A distributed file system that provides high-throughput access to application data.
• Hadoop YARN : A framework for job scheduling and cluster resource management.
• Hadoop Map Reduce : A YARN-based system for parallel processing of large data sets.

Other Hadoop-related projects at Apache include :

• Ambari™ : A web-based tool for provisioning, managing, and monitoring Apache Hadoop clusters which includes support for Hadoop HDFS, Hadoop Map Reduce, Hive, HCatalog, HBase, Zookeeper, Oozie, Pig and Sqoop. Ambari also provides a dashboard for viewing cluster health such as heat maps and ability to view Map Reduce, Pig and Hive applications visually along with features to diagnose their performance characteristics in a user-friendly manner.
• Avro™ : A data serialization system.
• Cassandra™ : A scalable multi-master database with no single points of failure.
• Chukwa™ : A data collection system for managing large distributed systems.
• HBase™ : A scalable, distributed database that supports structured data storage for large tables.
• Hive™ : A data warehouse infrastructure that provides data summarization and ad hoc querying.
• Mahout™ : A Scalable machine learning and data mining library.
• Pig™ : A high-level data-flow language and execution framework for parallel computation.
• ZooKeeper™ : A high-performance coordination service for distributed applications.