This document analyzes ways to improve the efficiency of Hadoop clusters for big data analysis. It first discusses how Hadoop uses the MapReduce framework to parallelize processing of large datasets across clusters of commodity hardware. It then describes three common techniques for providing fault tolerance in Hadoop - data replication, heartbeat messages, and checkpointing and recovery. Data replication stores duplicate copies of data on multiple nodes to allow recovery from failures. Heartbeat messages check that processing nodes remain active. Checkpointing saves processing state periodically to allow restarting from the last checkpoint if a failure occurs. The document aims to suggest methods for improving overall performance and fault tolerance of Hadoop clusters for big data analysis.