Chapter 2. Installing and configuring Instance HA

Red Hat OpenStack Platform (RHOSP) director deploys Instance High Availability (HA). However, you must perform additional steps to configure a new Instance HA deployment on a new overcloud. After you complete the steps, Instance HA will run on a subset of Compute nodes with a custom role.

Important

To enable instance HA in a different environment, such as an existing overcloud that uses standard or custom roles, perform only the procedures that are relevant to your deployment and adapt your templates accordingly.

2.1. Configuring the Instance HA role, flavor, and profile

Before deploying Instance HA, add the Instance HA role to your roles-data.yaml file, create the Instance HA flavor, tag each Comput node that you want to manage with Instanc HA with the Instance HA profile, and map the Instance HA role to the Instance HA flavor.

Note

You can modify the example file and role names in this procedure according to your environment.

Procedure

  1. Add the ComputeInstanceHA role to your roles-data.yaml file and regenerate the file.

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

    The ComputeInstanceHA role includes all the services in the default Compute role, the ComputeInstanceHA services, and the PacemakerRemote services.

  2. Create the compute-instance-ha flavor to tag the Compute nodes to manage with Instance HA.

    $ 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
    $ openstack flavor set --property resources:VCPU=0 --property resources:MEMORY_MB=0 --property resources:DISK_GB=0 --property resources:CUSTOM_BAREMETAL=1 compute-instance-ha
  3. Tag each Compute node that you want to manage with Instance HA with the compute-instance-ha profile, and replace <NODE UUID> with the actual UUID:

    $ 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 parameter:

    parameter_defaults:
      OvercloudComputeInstanceHAFlavor: compute-instance-ha

Additional resources

2.2. Enabling fencing on an overcloud with Instance HA

Enable fencing on all Controller and Compute nodes in the overcloud by creating an environment file with fencing information.

Procedure

  1. Create the environment file in an accessible location, such as ~/templates, and include the following content:

    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
  2. If you do not use shared storage for your Compute instance, add the following parameter to the environment file that you created:

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

2.3. Deploying the overcloud with Instance HA

If you already deployed the overcloud, rerun the openstack overcloud deploy command with the additional Instance HA files you created. You can configure Instance HA for your overcloud at any time after you create the undercloud.

Prerequisites

  • Instance HA role, flavor, and profile is configured.
  • Fencing is enabled on the overcloud.

Procedure

  • Use the openstack overcloud deploy command with the -e option for each environment file that you created and with the compute-instanceha.yaml environment file. Replace <FLAVOR_ENV_FILE> and <FENCING_ENV_FILE> with the appropriate file names in your environment:

    $ 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.
    • Include the full path to each environment file that you want to include in the overcloud deployment.

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

2.4. Testing Instance HA evacuation

To test that Instance HA evacuates instances correctly, you trigger evacuation on a Compute node and check that the Instance HA agents successfully evacuate and re-create the instance on a different Compute node.

Warning

The following procedure involves deliberately crashing a Compute node, which triggers the automated evacuation of instances with Instance HA.

Prerequisites

  • Instance HA is deployed on the Compute node.

Procedure

  1. Start one or more instances on the overcloud.

    stack@director $ . overcloudrc
    stack@director $ openstack server create --image cirros --flavor 2 test-failover
    stack@director $ openstack server list -c Name -c Status
  2. Log in to the Compute node that hosts the instances and change to the root user. Replace compute-n with the name of the Compute node:

    stack@director $ . stackrc
    stack@director $ ssh -l heat-admin compute-n
    heat-admin@compute-n $ su -
  3. Crash the Compute node.

    root@compute-n $ echo c > /proc/sysrq-trigger
  4. Wait a few minutes for the node to restart, and then verify that the instances from the Compute node that you crash are re-created on another Compute node:

    stack@director $ openstack server list -c Name -c Status
    stack@director $ openstack compute service list

2.5. Designating instances to evacuate with Instance HA

By default, Instance HA evacuates all instances from a failed node. You can configure Instance HA to only evacuate instances with specific images or flavors.

Prerequisites

  • Instance HA is deployed on the overcloud.

Procedure

  1. Log in to the undercloud as the stack user.
  2. Source the overcloudrc file:

    $ source ~/overcloudrc
  3. Use one of the following options:

    • Tag an image:

      (overcloud) $ openstack image set --tag evacuable <image_id>

      Replace <image_id> with the ID of the image that you want to evacuate.

    • Tag a flavor:

      (overcloud) $ openstack flavor set --property evacuable=true <flavor_id>

      Replace <flavor_id> with the ID of the flavor that you want to evacuate.

2.6. Additional resources