Apache Hadoop 2.7.1 is a minor release in the 2.x.y release line, building upon the previous release 2.7.0. This is the next stable release after Apache Hadoop 2.6.x.
Here is a short overview of the major features and improvements since 2.6.x.
The Hadoop documentation includes the information you need to get started using Hadoop. Begin with the Single Node Setup which shows you how to set up a single-node Hadoop installation. Then move on to the Cluster Setup to learn how to set up a multi-node Hadoop installation.