You have installed a cluster running HDFS and MapReduce version 2 (MRv2) on YARN. You have
no afs.hosts entry()ies in your hdfs-alte.xml configuration file. You configure a new worker node by
setting fs.default.name in its configuration files to point to the NameNode on your cluster, and you
start the DataNode daemon on that worker node.
What do you have to do on the cluster to allow the worker node to join, and start storing HDFS
blocks?
A.
Nothing; the worker node will automatically join the cluster when the DataNode daemon is
started.
B.
Without creating a dfs.hosts file or making any entries, run the command hadoop dfsadmin
–refreshHadoop on the NameNode
C.
Create a dfs.hosts file on the NameNode, add the worker node’s name to it, then issue the
command hadoop dfsadmin –refreshNodes on the NameNode
D.
Restart the NameNode