Downgrade HDFS DataNodes
Shut down the current DataNode:
su – hdfs -c "hdfs dfsadmin -shutdownDatanode <DATANODE_HOST:IPC_PORT> upgrade"
For example:
[hdp@node-1 ~]# su - hdfs -c 'hdfs dfsadmin -shutdownDatanode node-1.example.com:8010 upgrade' Submitted a shutdown request to datanode node-1.example.com:8010
Check to make sure the DataNode has stopped:
su – hdfs -c "hdfs dfsadmin -getDatanodeInfo <DATANODE_HOST:IPC_PORT>"
If the DataNode stopped successfully you’ll see a series of retry messages, followed by
Datanode unreachable
.Switch to the previous DataNode version, and then start the DataNode:
hdp-select set hadoop-hdfs-datanode 2.2.0.0-2041
su - hdfs -c "/usr/hdp/current/hadoop-hdfs-datanode/../hadoop/sbin/hadoop-daemon.sh start datanode"
To verify that the DataNode joined the HDFS cluster, list live HDFS processes:
su - hdfs -c "hdfs dfsadmin -report -live"
This should list the downgraded DataNode as a live node.
Type Control-C to exit the utility.