9. Verify HDFS filesystem health

Analyze if the filesystem is healthy.

Run the fsck command on namenode as $HDFS_USER:
su $HDFS_USER
hdfs fsck / -files -blocks -locations > dfs-new-fsck-1.log
Run hdfs namespace and report.
1. List directories.
  su -l <HDFS_USER>
  hdfs dfs -ls -R / > dfs-new-lsr-1.log
2. Run report command to create a list of DataNodes in the cluster.
  su -l <HDFS_USER>
  hdfs dfsadmin -report > dfs-new-report-1.log
3. Compare the namespace report before the upgrade and after the upgrade. Verify that user files exist after upgrade.
  su $HDFS_USER
  dfs-old-fsck-1.log < -- > dfs-new-fsck-1.log dfs-old-lsr-1.log < -- > dfs-new-lsr-1.log
  Note
  You must do this comparison manually to catch all errors.
4. From the Namenode WebUI, see if all DataNodes are up and running.
  http://<namenode>:50070

	Note
You must do this comparison manually to catch all errors.