High availability group policies

Every high availability group has a policy associated with it. This policy is used to determine which members of a high availability group are active at a given time.

The policies that the high availability groups use are stored as part of the core group configuration. The same policy can be used by several different high availability groups, but all of the high availability groups to which it applies must be part of the same core group. Before modifying or deleting an IBM® provided policy, read the topic High availability group policy modification guidelines.

Policy selection

Policies are statically configured, and the high availability groups that are governed by them are created dynamically. Therefore, a mechanism is required to associate a running high availability group to a configured policy. This association is accomplished by comparing the following two pieces of information.
  • The high availability group name
  • The policy match criteria

The High availability group policy modification guidelines topic provides more detail about how a policy is selected.

Policy settings

Some policy settings apply for all policy types while others only apply for specific policy types. Some of the policy settings also influence the overall behavior of a policy. The topic Implications of high availability group policy settings describes the various settings, the applicable policy types, and how they influence policy behavior.

Policy enforcement

Whenever one of the following conditions occurs, the high availability manager runs the policy that is associated with a high availability group and takes any appropriate action:
  • A member joins or leaves that high availability group. A member leaves the group if the member fails.
  • The state of a member of that high availability group changes. For example, if the state changes from idle to active, or from idle to disabled, the policy rules are reapplied.

Policy changes

The high availability manager dynamically detects policy configuration changes. Therefore, policy setting changes go into affect as soon as you save and propagate these changes. Server restarts are not required.