Stop all Application and Services other than HDFS
Run Fsck
hdfs fsck / -files -blocks -locations > dfs-fsck.log
Create Metadata Checkpoint
hdfs dfsadmin -safemode enter
hdfs dfsadmin -saveNamespace
Backup Checkpoint files
${dfs.namenode.name.dir}/current
Run dataNode Report
hdfs dfsadmin -report > dfs-report.log
Capture Namespace
hdfs dfs -ls -R / > dfs-lsr.log
Install new Hadoop Version..
Start Upgrade process
hadoop-daemon.sh start namenode -upgrade
Check status of upgrade
hadoop dfsadmin -upgradeProgress status
Finalize previous images
hdfs dfsadmin -finalizeUpgrade
Validate upgrade completes
hadoop dfsadmin -upgradeProgress status