5. So what exactly is Apache Hadoop ? It is a cluster technology with a single master and multiple slaves, designed for commodity hardware It consists of two runtimes, the Hadoop distributed file system ( HDFS ) and Map/Reduce As data is copied onto the HDFS, it ensures the data is blocked and replicated to other machines (node) to provide redundancy Self contained jobs are written in Map/Reduce and submitted to the cluster. The jobs run in parallel on each of the machines in the cluster, processing the data on the local machine ( data locality ). Hadoop may execute or re-execute a job on any node in the cluster. Node failures are automatically handled by the framework.
6. Hadoop – The Hadoop Cluster - Distributed File System - Map/Reduce