Hadoop version
CDH4 is based on Apache Hadoop 2.0.0 alpha, it also includes a number of enhancements and fixes above and beyond that release that will be available in subsequent Hadoop 2.x releases. Hadoop 2.0 was formerly known as Hadoop 0.23, and the CDH4 beta releases were based on Hadoop 0.23, but CDH4.0 (GA) is not. Thanks, Eli