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4.10. Adding a Cluster Service to the Cluster
To add a cluster service to the cluster, follow the steps in this section.
- From the cluster-specific page, you can add services to that cluster by clicking on Service Groups along the top of the cluster display. This displays the services that have been configured for that cluster. (From the Service Groups page, you can also start, restart, and disable a service, as described in Section 5.5, “Managing High-Availability Services”.)
- Click Add. This displays the Add Service Group to Cluster dialog box.
- On the Add Service Group to Cluster dialog box, at the Service Name text box, type the name of the service.
NoteUse a descriptive name that clearly distinguishes the service from other services in the cluster.
- Check the Automatically Start This Service check box if you want the service to start automatically when a cluster is started and running. If the check box is not checked, the service must be started manually any time the cluster comes up from the stopped state.
- Check the Run Exclusive check box to set a policy wherein the service only runs on nodes that have no other services running on them.
- If you have configured failover domains for the cluster, you can use the drop-down menu of the Failover Domain parameter to select a failover domain for this service. For information on configuring failover domains, see Section 4.8, “Configuring a Failover Domain”.
- Use the Recovery Policy drop-down box to select a recovery policy for the service. The options are to Relocate, Restart, Restart-Disable, or Disable the service.Selecting the Restart option indicates that the system should attempt to restart the failed service before relocating the service. Selecting the Relocate option indicates that the system should try to restart the service in a different node. Selecting the Disable option indicates that the system should disable the resource group if any component fails. Selecting the Restart-Disable option indicates that the system should attempt to restart the service in place if it fails, but if restarting the service fails the service will be disabled instead of being moved to another host in the cluster.If you select Restart or Restart-Disable as the recovery policy for the service, you can specify the maximum number of restart failures before relocating or disabling the service, and you can specify the length of time in seconds after which to forget a restart.
- To add a resource to the service, click Add Resource. Clicking Add Resource causes the display of the Add Resource To Service drop-down box that allows you to add an existing global resource or to add a new resource that is available only to this service.
NoteWhen configuring a cluster service that includes a floating IP address resource, you must configure the IP resource as the first entry.
- To add an existing global resource, click on the name of the existing resource from the Add Resource To Service drop-down box. This displays the resource and its parameters on the Service Groups page for the service you are configuring. For information on adding or modifying global resources, see Section 4.9, “Configuring Global Cluster Resources”).
- To add a new resource that is available only to this service, select the type of resource to configure from the Add Resource To Service drop-down box and enter the resource parameters for the resource you are adding. Appendix B, HA Resource Parameters describes resource parameters.
- When adding a resource to a service, whether it is an existing global resource or a resource available only to this service, you can specify whether the resource is an Independent Subtree or a Non-Critical Resource.If you specify that a resource is an independent subtree, then if that resource fails only that resource is restarted (rather than the entire service) before the system attempting normal recovery. You can specify the maximum number of restarts to attempt for that resource on a node before implementing the recovery policy for the service. You can also specify the length of time in seconds after which the system will implement the recovery policy for the service.If you specify that the resource is a non-critical resource, then if that resource fails only that resource is restarted, and if the resource continues to fail then only that resource is disabled, rather than the entire service. You can specify the maximum number of restarts to attempt for that resource on a node before disabling that resource. You can also specify the length of time in seconds after which the system will disable that resource.
- If you want to add child resources to the resource you are defining, click Add Child Resource. Clicking Add Child Resource causes the display of the Add Resource To Service drop-down box, from which you can add an existing global resource or add a new resource that is available only to this service. You can continue adding children resources to the resource to suit your requirements.
NoteIf you are adding a Samba-service resource, add it directly to the service, not as a child of another resource.
NoteWhen configuring a dependency tree for a cluster service that includes a floating IP address resource, you must configure the IP resource as the first entry and not as the child of another resource.
- When you have completed adding resources to the service, and have completed adding children resources to resources, click Submit. Clicking Submit returns to the Service Groups page displaying the added service (and other services).
As of Red Hat Enterprise Linux 6.9, the Service Groups display for a selected service group includes a table showing the actions that have been configured for each resource in that service group. For information on resource actions, see Appendix D, Modifying and Enforcing Cluster Service Resource Actions.
To verify the existence of the IP service resource used in a cluster service, you can use the
/sbin/ip addr showcommand on a cluster node (rather than the obsoleted
ifconfigcommand). The following output shows the
/sbin/ip addr showcommand executed on a node running a cluster service:
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1356 qdisc pfifo_fast qlen 1000 link/ether 00:05:5d:9a:d8:91 brd ff:ff:ff:ff:ff:ff inet 10.11.4.31/22 brd 10.11.7.255 scope global eth0 inet6 fe80::205:5dff:fe9a:d891/64 scope link inet 10.11.4.240/22 scope global secondary eth0 valid_lft forever preferred_lft forever
To modify an existing service, perform the following steps.
- From the Service Groups dialog box, click on the name of the service to modify. This displays the parameters and resources that have been configured for that service.
- Edit the service parameters.
- Click Submit.
To delete one or more existing services, perform the following steps.
- From the luci Service Groups page, click the check box for any services to delete.
- Click Delete.
- As of Red Hat Enterprise Linux 6.3, before luci deletes any services a message appears asking you to confirm that you intend to delete the service groups or groups, which stops the resources that comprise it. Click Cancel to close the dialog box without deleting any services, or click Proceed to remove the selected service or services.