Installation guide

HA Resource Behavior
This appendix describes common behavior of HA resources. It is meant to provide ancillary
information that may be helpful in configuring HA services. You can configure the parameters with
lu ci or by editing /etc/cl uster/cl uster.co nf. For descriptions of HA resource parameters,
refer to Appendix B, HA Resource Parameters. To understand resource agents in more detail you can
view them in /usr/share/cl uster of any cluster node.
Note
To fully comprehend the information in this appendix, you may require detailed understanding
of resource agents and the cluster configuration file, /etc/cl uster/cl uster. co nf.
An HA service is a group of cluster resources configured into a coherent entity that provides
specialized services to clients. An HA service is represented as a resource tree in the cluster
configuration file, /etc/cl uster/cluster. co nf (in each cluster node). In the cluster
configuration file, each resource tree is an XML representation that specifies each resource, its
attributes, and its relationship among other resources in the resource tree (parent, child, and sibling
relationships).
Note
Because an HA service consists of resources organized into a hierarchical tree, a service is
sometimes referred to as a resource tree or resource group. Both phrases are synonymous with
HA service.
At the root of each resource tree is a special type of resource — a service resource. Other types of
resources comprise the rest of a service, determining its characteristics. Configuring an HA service
consists of creating a service resource, creating subordinate cluster resources, and organizing them
into a coherent entity that conforms to hierarchical restrictions of the service.
This appendix consists of the following sections:
Section C.1, “ Parent, Child, and Sibling Relationships Among Resources”
Section C.2, “ Sibling Start Ordering and Resource Child Ordering”
Section C.3, “ Inheritance, the <resources> Block, and Reusing Resources”
Section C.4, “ Failure Recovery and Independent Subtrees”
Section C.5, “ Debugging and Testing Services and Resource Ordering”
Note
The sections that follow present examples from the cluster configuration file,
/etc/cl uster/cl uster.co nf, for illustration purposes only.
C.1. Parent , Child, and Sibling Relat ionships Among Resources
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