crm_node

crm_node is a command-line tool from the crmsh suite used to query and manage node information in Pacemaker-based clusters. It focuses on listing cluster nodes, displaying their status, and sometimes allowing for basic node-level operations or attribute adjustments. This tool helps administrators verify the cluster membership and diagnose node-related issues.

Purpose

• Node Querying: Retrieve and display a list of nodes that are part of the cluster, along with their status (e.g., online, standby, offline).

• Cluster Health Monitoring: Quickly assess the overall health of cluster nodes, which is essential for troubleshooting and ensuring that the cluster maintains quorum.

• Node Management: In some cases, it may allow for basic management operations such as setting a node into standby mode or querying node attributes.

Basic Syntax

crm_node [options] [command] [arguments]

Common Operations

• Listing Nodes:

  crm_node --list

  This command outputs a list of all nodes currently recognized in the cluster.

• Querying Node Status:

  crm_node --status <node_name>

  Replace <node_name> with the name or identifier of the node to display detailed status information, such as whether the node is online, its current role, and any relevant attributes.

• Help and Documentation:

  crm_node --help

  Displays available commands, options, and usage details for the tool.

Example Usage

1. List All Nodes in the Cluster:

   crm_node --list

   This command shows a summary of each node's presence in the cluster, making it easier to identify nodes that may be offline or not responding.

2. Display Detailed Status for a Specific Node:

   crm_node --status node1

   Replace node1 with the actual node name to see more detailed information such as the node's connectivity, roles, and any attributes set for that node.

Conclusion

crm_node is an essential tool for cluster administrators working with Pacemaker-managed environments. It provides a straightforward way to monitor and verify the nodes within a cluster, ensuring that all members are operating correctly and contributing to cluster quorum. For further details or advanced usage, you can refer to the built-in help documentation by running:

crm_node --help

This tool, alongside other crmsh utilities, helps maintain the overall health and stability of high-availability clusters by giving administrators direct insight into node status and configuration.