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.
A cluster is the smallest unit of disk space that can be allocated to a file, which is why clusters are often called allocation units. Wasted space is part of the process. If a volume uses clusters that contain 8,192 bytes, an 8,000 byte file will use one cluster, or 8,192 bytes on the disk.