Chapter 7. Keeping Things Running

Having a Hadoop cluster is not all about writing interesting programs to do clever data analysis. You also need to maintain the cluster, and keep it tuned and ready to do the data crunching you want.

In this chapter we will cover:

• More about Hadoop configuration properties

• How to select hardware for your cluster

• How Hadoop security works

• Managing the NameNode

• Managing HDFS

• Managing MapReduce

• Scaling the cluster

Although these topics are operationally focused, they do give us an opportunity to explore some aspects of Hadoop we have not looked at before. Therefore, even if you won't be personally managing the cluster, there should be useful information here for you too.