Whats new in version 2.2.0:
- This release has a number of significant highlights compared to Hadoop 1.x:
- YARN - A general purpose resource management system for Hadoop to allow MapReduce and other other data processing frameworks and services
- High Availability for HDFS
- HDFS Federation
- HDFS Snapshots
- NFSv3 access to data in HDFS
- Support for running Hadoop on Microsoft Windows
- Binary Compatibility for MapReduce applications built on hadoop-1.x
- Substantial amount of integration testing with rest of projects in the ecosystem
- A couple of important points to note while upgrading to hadoop-2.2.0:
- HDFS - The HDFS community decided to push the symlinks feature out to a future 2.3.0 release and is currently disabled.
- YARN/MapReduce - Users need to change ShuffleHandler service name from mapreduce.shuffle to mapreduce_shuffle.
Publisher review: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.
Operating system:Mac OS X
Hadoop 2.2.0 details 
