namenode is an alias for org.apache.nutch.ndfs.NDFS
The NDFS class holds the NDFS client and server.
DataNode controls just one critical table: block-> BLOCK_SIZE stream of bytes
This info is stored on disk (the NameNode is responsible for asking other machines to replicate the data). The DataNode reports the table's contents to the NameNode upon startup and every so often afterwards.
Usage: bin/nutch org.apache.nutch.ndfs.NDFS <port> <namespace_dir>