4.7. Configuring Fencing for Cluster Members

Once you have completed the initial steps of creating a cluster and creating fence devices, you need to configure fencing for the cluster nodes by following the steps in this section. Note that you must configure fencing for each node in the cluster.
The following sections provide procedures for configuring a single fence device for a node, configuring a node with a backup fence device, and configuring a node with redundant power supplies:

4.7.1. Configuring a Single Fence Device for a Node

Use the following procedure to configure a node with a single fence device.
  1. From the cluster-specific page, you can configure fencing for the nodes in the cluster by clicking on Nodes along the top of the cluster display. This displays the nodes that constitute the cluster. This is also the default page that appears when you click on the cluster name beneath Manage Clusters from the menu on the left side of the luci Homebase page.
  2. Click on a node name. Clicking a link for a node causes a page to be displayed for that link showing how that node is configured.
    The node-specific page displays any services that are currently running on the node, as well as any failover domains of which this node is a member. You can modify an existing failover domain by clicking on its name. For information on configuring failover domains, see Section 4.8, “Configuring a Failover Domain”.
  3. On the node-specific page, under Fence Devices, click Add Fence Method. This displays the Add Fence Method to Node dialog box.
  4. Enter a Method Name for the fencing method that you are configuring for this node. This is an arbitrary name that will be used by Red Hat High Availability Add-On; it is not the same as the DNS name for the device.
  5. Click Submit. This displays the node-specific screen that now displays the method you have just added under Fence Devices.
  6. Configure a fence instance for this method by clicking the Add Fence Instance button that appears beneath the fence method. This displays the Add Fence Device (Instance) drop-down menu from which you can select a fence device you have previously configured, as described in Section 4.6.1, “Creating a Fence Device”.
  7. Select a fence device for this method. If this fence device requires that you configure node-specific parameters, the display shows the parameters to configure. For information on fencing parameters, see Appendix A, Fence Device Parameters.

    Note

    For non-power fence methods (that is, SAN/storage fencing), Unfencing is selected by default on the node-specific parameters display. This ensures that a fenced node's access to storage is not re-enabled until the node has been rebooted. When you configure a device that requires unfencing, the cluster must first be stopped and the full configuration including devices and unfencing must be added before the cluster is started. For information on unfencing a node, see the fence_node(8) man page.
  8. Click Submit. This returns you to the node-specific screen with the fence method and fence instance displayed.