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5.2. Starting the Cluster Configuration Tool

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You can start the Cluster Configuration Tool by logging in to a cluster node as root with the ssh -Y command and issuing the system-config-cluster command. For example, to start the Cluster Configuration Tool on cluster node nano-01, do the following:
  1. Log in to a cluster node and run system-config-cluster. For example: 
    $  ssh -Y root@nano-01
  .
  .
  .
# system-config-cluster
  2. If this is the first time you have started the Cluster Configuration Tool, the program prompts you to either open an existing configuration or create a new one. Click Create New Configuration to start a new configuration file (refer to Figure 5.1, “Starting a New Configuration File”).
    Starting a New Configuration File

    Figure 5.1. Starting a New Configuration File

    Note

    The Cluster Management tab for the Red Hat Cluster Suite management GUI is available after you save the configuration file with the Cluster Configuration Tool, exit, and restart the the Red Hat Cluster Suite management GUI (system-config-cluster). (The Cluster Management tab displays the status of the cluster service manager, cluster nodes, and resources, and shows statistics concerning cluster service operation. To manage the cluster system further, choose the Cluster Configuration tab.)
  3. Clicking Create New Configuration causes the New Configuration dialog box to be displayed (refer to Figure 5.2, “Creating A New Configuration”). The New Configuration dialog box provides a text box for a cluster name and group boxes for the following configuration options: Choose Lock Method, Use Multicast (DLM clusters only), and Use a Quorum Disk (DLM clusters only). In most circumstances you only need to configure a cluster name and a lock method. Distributed Lock Manager (DLM) is the default lock method. To configure a GULM cluster, select Grand Unified Lock Manager (GULM). (Selecting Grand Unified Lock Manager (GULM) disables Use Multicast and Use a Quorum Disk, which are applicable only to DLM clusters). Use Multicast specifies whether a multicast address is used for cluster management communication among cluster nodes. Use Multicast is disabled (checkbox unchecked) by default. To use a multicast address for cluster management communication among cluster nodes, click the Use Multicast checkbox (enabled when checked). When Use Multicast is enabled, the Address text boxes are enabled; enter the multicast address into the Address text boxes. To use a quorum disk, click the Use a Quorum Disk checkbox and enter quorum disk parameters. The following quorum-disk parameters are available in the dialog box if you enable Use a Quorum Disk: Interval, TKO, Votes, Minimum Score, Device, Label, and Quorum Disk Heuristic. Table 5.1, “Quorum-Disk Parameters” describes the parameters.

    Important

    Quorum-disk parameters and heuristics depend on the site environment and 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

    It is probable that configuring a quorum disk requires changing quorum-disk parameters after the initial configuration. The Cluster Configuration Tool (system-config-cluster) provides only the display of quorum-disk parameters after initial configuration. If you need to configure quorum disk, consider using Conga instead; Conga allows modification of quorum disk parameters.
    Overall:
    While system-config-cluster provides several convenient tools for configuring and managing a Red Hat Cluster, the newer, more comprehensive tool, Conga, provides more convenience and flexibility than system-config-cluster. You may want to consider using Conga instead (refer to Chapter 3, Configuring Red Hat Cluster With Conga and Chapter 4, Managing Red Hat Cluster With Conga).
    Creating A New Configuration

    Figure 5.2. Creating A New Configuration

  4. When you have completed entering the cluster name and other parameters in the New Configuration dialog box, click OK. Clicking OK starts the Cluster Configuration Tool, displaying a graphical representation of the configuration (Figure 5.3, “The Cluster Configuration Tool”).
    The Cluster Configuration Tool

    Figure 5.3. The Cluster Configuration Tool

Table 5.1. Quorum-Disk Parameters
Parameter Description
Use a Quorum Disk Enables quorum disk. Enables quorum-disk parameters in the New Configuration dialog box.
Interval The frequency of read/write cycles, in seconds.
TKO The number of cycles a node must miss in order to be declared dead.
Votes The number of votes the quorum daemon advertises to CMAN when it has a high enough score.
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.
Quorum Disk Heuristics
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.
Score — The weight of this heuristic. Be careful when determining scores for heuristics. The default score for each heuristic is 1.
Interval — The frequency (in seconds) at which the heuristic is polled. The default interval for every heuristic is 2 seconds.
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