You have installed a cluster HDFS and MapReduce version 2 (MRv2) on YARN. You have
no dfs.hosts entry(ies) in your hdfs-site.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 sorting HDFS blocks?
A.
Without creating a dfs.hosts file or making any entries, run the commands
hadoop.dfsadminrefreshModes on the NameNode
B.
Restart the NameNode
C.
Creating a dfs.hosts file on the NameNode, add the worker Node’s name to it, then issue
the command hadoop dfsadmin –refresh Nodes = on the Namenode
D.
Nothing; the worker node will automatically join the cluster when NameNode daemon is
started