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Appendix E: Remove a Compute Node

This procedure details how to remove a compute node from the overcloud in order to scale down a deployed environment.

Before you begin:

  • Migrate all workloads to different hypervisors before you begin the compute node removal procedure.

  • The process below uses a hypothetical situation created in a lab environment. Keep in mind that the names, addresses, and other information will be different in your specific environment.

Remove a compute node from your environment:

In this situation, we want to remove a compute node in the context of the undercloud that is called host1. This is based on the entry found in the /var/lib/contrail_cloud/config/inventory.yml configuration file.

  1. From the undercloud, run:

    Your output will return something similar to below:

    Take note of the name overcloudx72-compkernel-1. This is the hostname of host1, in context of the overcloud.

  2. Run the following command from the undercloud to prevent workloads from being scheduled on the given hypervisor:

    We have now marked overcloudx72-compkernel-1 as disabled, and all future workloads will not be placed on this target hypervisor.

  3. Verify that the hypervisor no longer holds any workloads. Run the following command from the undercloud:

    This command should return an empty result.

    If the hypervisor has remaining workloads, you need to migrate that workload before continuing.

  4. From the jumphost, modify your /var/lib/contrail_cloud/config/compute-nodes.yml configuration file by adding status: "deleting" under the node to be deleted. See below for an example entry in the compute-nodes.yml configuration file:
  5. From the jumphost, run:

    It is important to note that this will remove the compute node from the overcloud. However, the compute node will still be shown on the hypervisor, and will be reported as down. It is normal for the node to remain in the output of “nova hypervisor-list” after being removed from the overcloud. Upon completion of this procedure, the compute node is effectively considered removed from your deployed environment.

  6. Remove the node entry from the satellite. From the jumphost, run:

    Replace USERNAME and PASSWORD with your username and password.

    Replace with the global["domain"] value found in your site.yml configuration file.

  7. Completely remove the node entry from your compute-nodes.yml configuration file.
  8. Delete the node from your undercloud inventory.

    From the jumphost, modify your /var/lib/contrail_cloud/config/inventory.yml configuration file by adding the line status: "deleting" under the node in question. See below for an example entry in the inventory.yml configuration file:

  9. Run the script to complete the deletion of the node:
  10. Validate that the node has been removed from your inventory.

    From the undercloud, run:

    The output should no longer show host1.

  11. Finalize the procedure by removing the host entry from your /var/lib/contrail_cloud/config/inventory.yml configuration file.