Setting Up Red Hat Cluster

After you have successfully installed the clustering software on each cluster node, you should set up a Red Hat cluster that will ensure the high-availability of your Virtuozzo Containers 4.0 installations. You can use one of the following tools to set up a new cluster:

• system-config-cluster: this GUI tool can be used to easily install, configure, and manage Red Hat clusters.
• Conga: this comprehensive user interface can be used for installing, configuring, and managing Red Hat clusters, servers, and storage devices attached to clusters and servers.
• command line tools: this is a set of command line tools for configuring and managing Red Hat clusters.

The example below demonstrates how to set up a new Red Hat cluster using the system-config-cluster cluster configuration GUI tool:

1. Log in to any of you cluster nodes (this node should have the 'X-Window' component installed) and launch the Cluster Configuration Tool as follows:

   # system-config-cluster

2. Your further steps will be different depending on whether you are starting the tool for the first time or have already launched it before:
   • click Create New Configuration in the displayed dialog window if you are running the Cluster Configuration Tool for the first time;
   • otherwise, click File -> New.
3. In the New Configuration window, enter a descriptive name for the cluster in the field provided and click OK. Please keep in mind that you will need to specify this name when creating a GFS file system with the gfs_mkfs utility. Please see Step 4 in the Configuring Shared Storage subsection for more information.
4. Set one or more fence devices for the cluster:
   • Select the Fence Devices item and click Add a Fence Device at the bottom of the Cluster Configuration window:

     

   • In the Fence Device Configuration window, select the type of fence device to configure and provide the necessary information in the appropriate fields.

     Note: Please refer to the Configuring and Managing a Red Hat Cluster document for detailed information on available fence devices and their parameters.

   • Click OK.
5. Add all your Virtuozzo servers to the cluster:
   • Select the Cluster Nodes item and click Add a Cluster Node at the bottom of the Cluster Configuration window.
   • In the Node Properties window, type the name of the server you wish to add to the cluster (or its IP address on the cluster subnet) and click OK. For example:

     

   • Configure fencing for the added node using the Manage Fencing For This Node button at the bottom of the Cluster Configuration right frame.
   • Repeat the aforementioned operations for each Virtuozzo server to be included in the cluster.
6. Add one or more failover domains to the cluster. This step is optional and should be performed if you wish to specify one or more subsets of cluster nodes that will be eligible to run the corresponding cluster services. For more information on cluster services, please refer to the Creating and Configuring Cluster Services subsection.
   • Select the Failover Domains item and click Create a Failover Domain at the bottom of the Cluster Configuration window:

     

   • Type an arbitrary name for the failover domain (it will be used to distinguish the given failover domain among the other domains in the cluster) and click OK.
   • In the Failover Domain Configuration window, specify the cluster nodes to be included in the failover domain, configure the domain properties (e.g. set the cluster nodes prioritization), and click Close.

     Note: Each failover domain must contain at least one standby node where all Virtuozzo mission-critical services and Containers will be able to fail over in the event of an active node failure.

7. Save the current cluster configuration by clicking File --> Save on the main menu of the Cluster Configuration Tool. By default, you are offered to save the cluster configuration into the cluster.conf file in the /etc/cluster directory. Click OK to confirm the offered file name and location or change them to your preference.
8. Distribute the cluster configuration file (/etc/cluster/cluster.conf by default) to all nodes in the cluster. For example, you can do it using the scp utility.
9. Start the Red Hat clustering service on each server in the cluster by executing the following command:

   # service cman start

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