How to check node information in Hadoop?

To view node information in the Hadoop cluster, there are several methods available.

1. Hadoop Web Interface: Hadoop offers a web interface where users can access and view information about the cluster’s nodes through a browser. By default, the address for this interface is http://:50070/ (where is the hostname or IP address of the NameNode). On this interface, users can see the status of nodes in the cluster, storage capacity, running tasks, and other information.
2. Command Line: Node information can be viewed using Hadoop’s command line tools. For instance, the following command can be used to check the status of nodes in the cluster:
3. Generate a report using the HDFS administration command.
4. This command will display the status information of all nodes, including the hostname, storage capacity, used capacity, remaining capacity, and so on.
5. JMX monitoring: Hadoop also supports monitoring cluster node information using JMX (Java Management Extensions). It allows users to access various metrics of nodes such as CPU usage, memory usage, disk capacity, etc. Tools like JConsole or VisualVM can be used to connect to nodes in the cluster and view their information.

In general, the above methods provide different levels of node information, and users can choose the appropriate method to view node information based on specific needs.