Working with Application Groups

An application group is a resource that both summarizes the status of other resources (its members) and controls the activation of those members.

A special feature is that the members can inherit the group's dependencies.

Each member is a resource, as is the group itself. This means that groups can contain other groups. You can issue commands to start or stop groups as an entity. Also, you can link a group to a service period and thus schedule it automatically.

Detailed information about how to organize applications into a group, nest groups into other groups, and generate resources from groups and applications is provided in IBM Z® System Automation Defining Automation Policy.

The concept of resources allows you to dynamically move applications and groups from one system to another system in the sysplex. This move is achieved by stopping an active set of resources and starting an alternate set in a coordinated fashion. With this concept, you can also start and stop equivalent resources to maintain a desired level of server capacity.

There are two types of application groups:

  • System Application Groups: Application groups that are associated with particular systems.
  • Sysplex Application Groups: Application groups that are associated with a certain sysplex. The application group members can be spread over multiple systems within this sysplex.

Groups can also have one of three different natures (see Figure 1):

BASIC
In a BASIC application group all of its components must be available before the group is considered to be available.
MOVE
In a MOVE application group exactly one of its components must be available before the group is considered to be available. In MOVE groups you can specify alternative components that will be started if the primary component fails to start.
SERVER
In a SERVER application group any number of components can be specified that must be available before the group is considered to be available. With SERVER application groups you can specify what should happen if their components fail to start.

The automation administrator can set the numbers of members that should be available for a SERVER application group by specifying the Availability Target when defining the group.

Figure 1. Natures of Application Groups
Natures of Application Groups

Preference values are used for SERVER and MOVE groups to determine which members should preferably be made available.

For detailed information on how to define application groups and what nature to use for different purposes, refer to IBM Z System Automation Defining Automation Policy.

You can use the DISPAPG command to display detailed information about an application group from the automation agent point of view, such as automation agent or automation manager related information or automation policy information.