Apache Hadoop 2.2.0 稳定版发布了，建议用户升级。该版本更加稳定，同时在 API 和协议上兼容老的版本。 与 Hadoop 1.x 比较，该版本显著的改进包括： - 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
升级到 Hadoop 2.2.0 需要注意的有： - 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.
更多详细介绍请看 Hadoop 2.2.0 Release Notes | 
