Hadoop – Best Open Source Distributed System
Hadoop is a Free Java software framework that supports distributed applications running on large clusters of commodity computers that process huge amounts of data. It is a top level Apache project.
Hadoop implements a computational paradigm named Map/Reduce, where the application is divided into many small fragments of work, each of which may be executed or reexecuted on any node in the cluster. In addition, it provides a distributed file system (HDFS) that stores data on the compute nodes, providing very high aggregate bandwidth across the cluster. Both Map/Reduce and the distributed file system are designed so that node failures are automatically handled by the framework.
[Source: Wiki]
Detail Implementation of Hadoop
Download: Hadoop