High availability groups are dynamically created components of a core group. They cannot be configured directly but are directly affected by static data, such as policy configurations, which are specified at the core group level.
A high availability group cannot extend beyond the boundaries of a core group. However, members of a high availability group can also be members of other high availability groups as long as all of these high availability groups are defined within the same core group.
Whenever transaction manager code creates a high availability group, the high availability manager matches the match criteria of the Clustered TM Policy to the high availability group member name. In this example, the string type=WAS_TRANSACTIONS included in the high availability group name is matched to the same string in the policy match criteria for the Clustered TM Policy. This match associates the Clustered TM Policy with the high availability group the transaction manager component creates.
After a policy is established for a high availability group, you can change some of the policy attributes, such as quorum, fail back, and preferred servers. However, you can not change the policy type. If you need to change the policy type, you must create a new policy and then use the match criteria to associate it with the appropriate group.
If you want to use the same match criteria, you must delete the old policy before defining the new policy. You cannot use the same match criteria for two different policies.
Before changing the policy type for a high availability group you must fully understand how the application server processes that are contained in that high availability group are configured and how they will be affected by the policy change. You must also verify that the component that uses that particular high availability group supports the new policy type. For example, if the high availability group for the service integration bus uses a One of N policy, because it only wants one server to be active at any given point in time, and you change the policy associated with that group to All Active, the service integration bus high availability support no longer functions properly and data corruption might occur.
Related tasks
Creating a policy for a high availability group
Changing the policy of a high availability group
Changing the configuration of a high availability group