D.1. Parent, Child, and Sibling Relationships Among Resources

A cluster service is an integrated entity that runs under the control of rgmanager. All resources in a service run on the same node. From the perspective of rgmanager, a cluster service is one entity that can be started, stopped, or relocated. Within a cluster service, however, the hierarchy of the resources determines the order in which each resource is started and stopped.The hierarchical levels consist of parent, child, and sibling.

Example D.1, “Resource Hierarchy of Service foo” shows a sample resource tree of the service foo. In the example, the relationships among the resources are as follows:

fs:myfs (<fs name="myfs" ...>) and ip:10.1.1.2 (<ip address="10.1.1.2 .../>) are siblings.
fs:myfs (<fs name="myfs" ...>) is the parent of script:script_child (<script name="script_child"/>).
script:script_child (<script name="script_child"/>) is the child of fs:myfs (<fs name="myfs" ...>).

<service name="foo" ...>
    <fs name="myfs" ...>
        <script name="script_child"/>
    </fs>
    <ip address="10.1.1.2" .../>
</service>

Example D.1. Resource Hierarchy of Service foo

The following rules apply to parent/child relationships in a resource tree:

Parents are started before children.
Children must all stop cleanly before a parent may be stopped.
For a resource to be considered in good health, all its children must be in good health.