dfsadmin

• Hadoop
• HDFS

• HDFS dfsadmin Command Reference

Put the cluster in Safemode:

hdfs dfsadmin -safemode enter

Recommission or decommission DataNode(s):

hdfs dfsadmin -refreshNodes

Get information about your HDFS filesystem:

hdfs dfsadmin -report

Check the status of the nodes in the rack

hdfs dfsadmin -printTopology