7. Verify HDFS filesystem health

Analyze if the filesystem is healthy.

Run the fsck command on namenode as $HDFS_USER:
hdfs fsck / -files -blocks -locations > dfs-new-fsck-1.log
Run hdfs namespace and report.
1. List directories.
  hdfs dfs -ls
2. Run report command to create a list of DataNodes in the cluster.
  hdfs dfsadmin -report > dfs-new-report-1.log
Compare the namespace report before the upgrade and after the upgrade. Verify that user files exist after upgrade.
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.
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.