what is a single node cluster
Single Node or Psuedo-Distributed Cluster is the one in which all the essential daemons (like NameNode, DataNode, JobTracker and TaskTracker) run on the same machine. The default replication factor for a single node cluster is 1. A single node cluster is basically used to simulate a full cluster like environment and to test hadoop applications and unlike the Stand-alone mode, HDFS is accessible in this.