title: Spark Driver in Apache spark
body: <p>I already have a cluster of 3 machines (ubuntu1,ubuntu2,ubuntu3 by VM virtualbox) running Hadoop 1.0.0. I installed spark on each of these machines. ub1 is my master node and the other nodes are working as slave. My question is what exactly a spark driver is? and should we set a IP and port to spark driver by <code>spark.driver.host</code> and where it will be executed and located? (master or slave)</p>