The Role of Service Group Dependencies

A service group dependency provides a mechanism by which two service groups can be linked by a dependency rule. In a service group dependency:

• A service group that depends on other service groups is a parent group.
• A service group on which other service groups depend is a child group.
• A service group can function as both parent and child.

Parent and child service groups are linked by a rule. This link defines the behavior of the groups when one of them faults. A link can be configured according to the following criteria:

• The category of the dependency, such as online or offline (described in Categories of Service Group Dependencies).
• The location of the dependency, such as local, global, or remote (described in Location of Dependency).
• The type of dependency, such as soft, firm, or hard (described in Type of Dependency).

Each service group dependency can be associated with a category, location, and type. For example, you could have an online local soft dependency. Note that all combinations of category, location, and dependency type are not supported.

Based on the type of link, VCS brings the parent/child service group online or takes it offline when one of the linked service groups faults.The link also controls the location where VCS brings a group online following events such as a resource fault, automatic group start, system shutdown, etc.