High availability group policy modification guidelines
Do not delete the default IBM provided policies
Rather, create a new policy with more specific match criteria.
The policy with the greatest number of matches is the one used. Not deleting the IBM provided policy enables you to revert back to that policy if a problem occurs with the new policy.
Do not try to change the type of an existing policy
After a policy for a HA group is created, we can change some of the policy attributes such as preferred servers, or failback, but we cannot change the policy type. To change the policy type, create a new policy and then use match criteria to associate it with the appropriate HA group.
Verify which policies a component supports before creating a new policy to associate with that group
Before changing the policy associated with a given HA group, verify the appserver code using that HA group supports the change. For example, to change the type of policy that is associated with the HA group used by the transaction manager component, make sure the transaction manager code supports the new policy type before making the change.
Do not use the same match criteria for multiple policies in the same core group
If we have multiple policies configured with identical match criteria, the policy match to the associated HA group is ambiguous. If creating a new policy to replace an older policy createdd, we might need to delete the older policy to specify the appropriate match criteria. Another alternative is to specify additional match criteria in each policy so no ambiguity exists as to which policy is controlling the HA group.
Related concepts
High availability group policy selection process
High availability group policies