Chapter 3. Installing and configuring Instance HA

Instance HA is deployed and configured with the director. However, there are a few additional steps that you need to perform to prepare for the deployment.

This section includes all the steps needed to configure a new Instance HA deployment on a new overcloud with the goal of enabling Instance HA on a subset of Compute nodes with a custom role.

Important
  • Compute node host names and Pacemaker remote resource names must comply with the W3C naming conventions. For more information, see Declaring Namespaces and Names and Tokens in the W3C documentation.
  • If you deploy Instance HA in a Spine-Leaf environment, you must define a single internal_api network for the Controller and Compute nodes. You can then define a subnet for each leaf. For more information about configuring Spine-Leaf networks, see Creating a roles data file in the Spine Leaf Networking guide.
  • If you want to enable instance HA in a different environment, such as an existing overcloud using either standard or custom roles, follow only the procedures that are relevant to your deployment and adapt your templates accordingly.
  • Disabling Instance HA with the director after installation is not supported. For a workaround to manually remove Instance HA components from your deployment, see the article How can I remove Instance HA components from the controller nodes? . This workaround is provided as-is. You must verify the procedure in a test environment before implementing in production.

For general information on deploying the overcloud, see the Director Installation and Usage guide. For information on custom roles, see Composable Services and Custom Roles.

Configure the Instance HA role, flavor, and profile

  1. Add the ComputeInstanceHA role to your roles data file and regenerate the file. For example: 

    $ openstack overcloud roles generate -o ~/my_roles_data.yaml Controller Compute ComputeInstanceHA

    The ComputeInstanceHA role includes all the services in the default Compute role as well as the ComputeInstanceHA and the PacemakerRemote services. For general information about custom roles and about the roles-data.yaml, see the Roles section in the Advanced Overcloud Customization guide.

  2. Create the compute-instance-ha flavor to tag Compute nodes that you want to designate for Instance HA. For example: 

    $ source ~/stackrc
$ openstack flavor create --id auto --ram 6144 --disk 40 --vcpus 4 compute-instance-ha
$ openstack flavor set --property "cpu_arch"="x86_64" --property "capabilities:boot_option"="local" --property "capabilities:profile"="compute-instance-ha" compute-instance-ha

  3. Tag each Compute node that you want to designate for Instance HA with the compute-instance-ha profile. 

    $ openstack baremetal node set --property capabilities='profile:compute-instance-ha,boot_option:local' <NODE UUID>

  4. Map the ComputeInstanceHA role to the compute-instance-ha flavor by creating an environment file with the following content: 

    parameter_defaults:
  OvercloudComputeInstanceHAFlavor: compute-instance-ha

Enable fencing

  1. Enable fencing on all Controller and Compute nodes in the overcloud by creating an environment file with fencing information. Make sure to create the environment file in an accessible location, such as ~/templates. For example: 

    parameter_defaults:
  EnableFencing: true
  FencingConfig:
    devices:
    - agent: fence_ipmilan
      host_mac: 00:ec:ad:cb:3c:c7
      params:
        login: admin
        ipaddr: 192.168.24.1
        ipport: 6230
        passwd: password
        lanplus: 1
    - agent: fence_ipmilan
      host_mac: 00:ec:ad:cb:3c:cb
      params:
        login: admin
        ipaddr: 192.168.24.1
        ipport: 6231
        passwd: password
        lanplus: 1
    - agent: fence_ipmilan
      host_mac: 00:ec:ad:cb:3c:cf
      params:
        login: admin
        ipaddr: 192.168.24.1
        ipport: 6232
        passwd: password
        lanplus: 1
    - agent: fence_ipmilan
      host_mac: 00:ec:ad:cb:3c:d3
      params:
        login: admin
        ipaddr: 192.168.24.1
        ipport: 6233
        passwd: password
        lanplus: 1
    - agent: fence_ipmilan
      host_mac: 00:ec:ad:cb:3c:d7
      params:
        login: admin
        ipaddr: 192.168.24.1
        ipport: 6234
        passwd: password
        lanplus: 1

    For more information about fencing and STONITH configuration, see the Fencing Controller Nodes with STONITH section of the High Availability Deployment and Usage guide.

  2. Instance HA uses shared storage by default. If shared storage is not configured for your Compute instance, then add the following parameter to the environment file that you created in the previous step: 

    parameter_defaults:
  ExtraConfig:
    tripleo::instanceha::no_shared_storage: true

    See Section 3.1, “Considerations for Shared Storage” for details on how to boot from an OpenStack Block Storage (cinder) volume rather than configuring shared storage for the disk image of instances.

Deploy the overcloud

Run the openstack overcloud deploy command with the -e option for each environment file that you created, as well as the compute-instanceha.yaml environment file. For example: 

$ openstack overcloud deploy --templates \
  -e <FLAVOR_ENV_FILE> \
  -e <FENCING_ENV_FILE> \
  -e /usr/share/openstack-tripleo-heat-templates/environments/compute-instanceha.yaml
Note
  • Do not modify the compute-instanceha.yaml environment file.
  • Make sure to include the path to each environment file that you want to include in the overcloud deployment.
  • You can configure Instance HA for your overcloud at any time after creating the undercloud. If you already deployed the overcloud, you need to rerun the overcloud deploy command with the new Instance HA files.

After the deployment is complete, each Compute node will include a STONITH device and a GuestNode service.

3.1. Considerations for Shared Storage

Typically, Instance HA requires that you configure shared storage for disk images of instances. Therefore, if you attempt to use the no-shared-storage option, you might receive an InvalidSharedStorage error during evacuation, and the instances will not boot on another Compute node.

However, if all your instances are configured to boot from an OpenStack Block Storage (cinder) volume, you do not need to configure shared storage for the disk image of instances, and you can still evacuate all instances using the no-shared-storage option.

During evacuation, if your instances are configured to boot from a Block Storage volume, any evacuated instances should boot from the same volume on another Compute node. As a result, the evacuated instances immediately restart their jobs because the OS image and the application data are stored on the OpenStack Block Storage volume..