Every high availability group has a unique group name that consists of a set of name-value pairs. Every policy definition contains an attribute called match criteria that is also a set of name-value pairs. To determine the policy for a high availability group, the group name is compared to the match criteria of all the associated core group polices. The policy with the strongest match to the group name is assigned to the high availability group:
Any component can create a high availability group for that component to use. However, the component code must specify the name-value pairs that are used for the high availability group name. The WebSphere Application Server administrator can control the name-value pairs that make up a policy match criteria, and thereby control which policy governs a particular high availability group.
WebSphere Application Server includes a couple of predefined policies. The following examples demonstrate the matching mechanism that is used for these policies.
Clustered TM Policy
GN_PS=testCell\testNode\ServerA,IBM_hc=MyCluster,type=WAS_TRANSACTIONS
Administrator TM Policy
This example builds on the previous example and demonstrates how an administrator can define a new policy to govern the transaction manager high availability group. In this example the same high availability group name and default policies that are described in the previous example are used. However, in this example, the administrator creates a new policy in the DefaultCoreGroup configuration called the Administrator TM Policy. For the high availability manager to select this new policy, the policy must be eligible and contain more matches than any other policy.
The following description illustrates why, under these conditions, the Administrator TM Policy policy is selected for the transaction manager high availability group:
GN_PS=testCell\testNode\ServerA,IBM_hc=MyCluster,type=WAS_TRANSACTIONS
Because Administrator TM Policy has two matching pairs, IBM_hc=MyCluster and type=WAS_TRANSACTIONS, and Clustered TM Policy has only one matching pair, type=WAS_TRANSACTIONS, the high availability manager associates Administrator TM Policy with the transaction manager high availability group.
Ambiguous Matches
HMGR0301W: No policy was located for the group named {0} HMGR0302W: Multiple policies match the group named {0}, Matching Policies are {1}
You can use the administrative console to view the policies associated with a high availability group and the current state of members of that group.
Related concepts
High availability groups
High availability group policies