3.4. Global Cluster Properties

When a cluster is created, or if you select a cluster to configure, a cluster-specific page is displayed. The page provides an interface for configuring cluster-wide properties and detailed properties. You can configure cluster-wide properties with the tabbed interface below the cluster name. The interface provides the following tabs: General, GULM (GULM clusters only), Fence (DLM clusters only), Multicast (DLM clusters only), and Quorum Partition (DLM clusters only). To configure the parameters in those tabs, follow the steps in this section. If you do not need to configure parameters in a tab, skip the step for that tab.
  1. General tab — This tab displays cluster name and provides an interface for configuring the configuration version and advanced cluster properties. The parameters are summarized as follows:
    • The Cluster Name text box displays the cluster name; it does not accept a cluster name change. You cannot change the cluster name. The only way to change the name of a Red Hat cluster is to create a new cluster configuration with the new name.
    • The Configuration Version value is set to 1 by default and is automatically incremented each time you modify your cluster configuration. However, if you need to set it to another value, you can specify it at the Configuration Version text box.
    • You can enter advanced cluster properties by clicking Show advanced cluster properties. Clicking Show advanced cluster properties reveals a list of advanced properties. You can click any advanced property for online help about the property.
    Enter the values required and click Apply for changes to take effect.
  2. Fence tab (DLM clusters only) — This tab provides an interface for configuring these Fence Daemon Properties parameters: Post-Fail Delay and Post-Join Delay. The parameters are summarized as follows:
    • The Post-Fail Delay parameter is the number of seconds the fence daemon (fenced) waits before fencing a node (a member of the fence domain) after the node has failed. The Post-Fail Delay default value is 0. Its value may be varied to suit cluster and network performance.
    • The Post-Join Delay parameter is the number of seconds the fence daemon (fenced) waits before fencing a node after the node joins the fence domain. The Post-Join Delay default value is 3. A typical setting for Post-Join Delay is between 20 and 30 seconds, but can vary according to cluster and network performance.
    Enter values required and Click Apply for changes to take effect.

    Note

    For more information about Post-Join Delay and Post-Fail Delay, refer to the fenced(8) man page.
  3. GULM tab (GULM clusters only) — This tab provides an interface for configuring GULM lock servers. The tab indicates each node in a cluster that is configured as a GULM lock server and provides the capability to change lock servers. Follow the rules provided at the tab for configuring GULM lock servers and click Apply for changes to take effect.

    Important

    The number of nodes that can be configured as GULM lock servers is limited to either one, three, or five.
  4. Multicast tab (DLM clusters only) — This tab provides an interface for configuring these Multicast Configuration parameters: Do not use multicast and Use multicast. Multicast Configuration specifies whether a multicast address is used for cluster management communication among cluster nodes. Do not use multicast is the default setting. To use a multicast address for cluster management communication among cluster nodes, click Use multicast. When Use multicast is selected, the Multicast address and Multicast network interface text boxes are enabled. If Use multicast is selected, enter the multicast address into the Multicast address text box and the multicast network interface into the Multicast network interface text box. Click Apply for changes to take effect.
  5. Quorum Partition tab (DLM clusters only) — This tab provides an interface for configuring these Quorum Partition Configuration parameters: Do not use a Quorum Partition, Use a Quorum Partition, Interval, Votes, TKO, Minimum Score, Device, Label, and Heuristics. The Do not use a Quorum Partition parameter is enabled by default. Table 3.1, “Quorum-Disk Parameters” describes the parameters. If you need to use a quorum disk, click Use a Quorum Partition, enter quorum disk parameters, click Apply, and restart the cluster for the changes to take effect.

    Important

    Quorum-disk parameters and heuristics depend on the site environment and the special requirements needed. To understand the use of quorum-disk parameters and heuristics, refer to the qdisk(5) man page. If you require assistance understanding and using quorum disk, contact an authorized Red Hat support representative.

    Note

    Clicking Apply on the Quorum Partition tab propagates changes to the cluster configuration file (/etc/cluster/cluster.conf) in each cluster node. However, for the quorum disk to operate, you must restart the cluster (refer to Section 4.1, “Starting, Stopping, and Deleting Clusters”).

Table 3.1. Quorum-Disk Parameters

Parameter Description
Do not use a Quorum Partition Disables quorum partition. Disables quorum-disk parameters in the Quorum Partition tab.
Use a Quorum Partition Enables quorum partition. Enables quorum-disk parameters in the Quorum Partition tab.
Interval The frequency of read/write cycles, in seconds.
Votes The number of votes the quorum daemon advertises to CMAN when it has a high enough score.
TKO The number of cycles a node must miss to be declared dead.
Minimum Score The minimum score for a node to be considered "alive". If omitted or set to 0, the default function, floor((n+1)/2), is used, where n is the sum of the heuristics scores. The Minimum Score value must never exceed the sum of the heuristic scores; otherwise, the quorum disk cannot be available.
Device The storage device the quorum daemon uses. The device must be the same on all nodes.
Label Specifies the quorum disk label created by the mkqdisk utility. If this field contains an entry, the label overrides the Device field. If this field is used, the quorum daemon reads /proc/partitions and checks for qdisk signatures on every block device found, comparing the label against the specified label. This is useful in configurations where the quorum device name differs among nodes.
Heuristics
Path to Program — The program used to determine if this heuristic is alive. This can be anything that can be executed by /bin/sh -c. A return value of 0 indicates success; anything else indicates failure. This field is required.
Interval — The frequency (in seconds) at which the heuristic is polled. The default interval for every heuristic is 2 seconds.
Score — The weight of this heuristic. Be careful when determining scores for heuristics. The default score for each heuristic is 1.
Apply Propagates the changes to the cluster configuration file (/etc/cluster/cluster.conf) in each cluster node.