There is nothing sacred about electrons being called negative charge and protons positive charge.Itâs just a convention. You, can very well call electrons as positive charge and protons as negative charge!
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.
It is also necessary to implement fault tolerance or error. recovery features; that is, when a node fails, or is removed from the cluster, the rest of the processes running on the. cluster can continue to function. The cluster operating system should be scalable, and should provide that the system. is highly available. Implementing a SSI involves making the cluster appear to be a single computer to the users, and to the network. the cluster is connected to. The SSI should implement a single entry point to the cluster, a single file hierarchy. (usually implementing error-recovery using journalling), a single control point, virtual networking, single memory. space, single job management, and a single user interface.