Upgrade Hadoop

This section contains instructions to Upgrade Hadoop from one version to another. This tutorial explain how to Upgrade Hadoop, which is running in distributed mode(ie on cluster) without loss of data. Before starting upgrade procedure please ensure that no job is running.

COMMAND	DESCRIPTION
bin/stop-mapred.sh	Stop map-reduce cluster(s) and all client applications running on the DFS cluster
bin/stop-dfs.sh	Stop DFS using the shutdown command.
	Install new version of Hadoop (On all the nodes in the cluster)
bin/start-dfs.sh -upgrade	Start DFS cluster with -upgrade option
bin/start-mapred.sh	Start map-reduce cluster
bin/hadoop dfsadmin --finalizeUpgrade	Verify the components run properly and then finalize the upgrade when convinced
If you get any error visit Hadoop Troubleshooting