Network Deployment (Distributed operating systems), v8.0 > Establishing high availability > Configure core groups
Specify a preferred server for messaging requests
If a core group includes a cluster of application servers, and a messaging engine is configured for that cluster, any of the servers in that cluster can handle work items for the messaging engine. The default message provider that is included in the product is based on Service Integration Bus (SIB) technology, and is governed by the Default SIBus policy, which is a One of N policy. This policy ensures that only one of the application servers in the cluster is active at a time). We can modify the high availability group policy to specify that a specific cluster member handles the messaging work. Before specifying a preferred server for messaging requests:
For high availability, configure a messaging engine to run in a cluster. However, you might want a specific cluster member to handle the messaging requests. Another member of the cluster should handle the messaging requests only if the preferred member fails.
- You should review the following topics:
- High availability groups
- High availability group policy modification guidelines
- High availability group policies
- We must determine:
- The name of the core group that includes the server to handle messaging requests.
- The name of the high availability group for the messaging function.
- The name of the policy that is associated with this high availability group
- Create a new policy specific to the high availability group that controls the messaging engine cluster, if one does not already exist.
It is possible for a single policy to govern several different high availability groups. Therefore, to modify the policy for cluster scoped control, create a new policy specific to the high availability group that controls the messaging engine cluster. See Create a policy for a high availability group for more information on how to create this policy.
After creation of the new policy and associate the policy with the high availability group for a given cluster, We can specify a preferred server for messaging requestws..
- In the admin console, click...
Servers > Core Groups > Core group settings > core_group_name.
- Click the Runtime tab to determine both the name of the high availability group, and the name of the policy that is currently controlling the group. See View high availability group information for more information on how to perform this step. We must have at least one of the group members running.
- In the admin console, click...
Servers > Core Groups > Core group settings > core_group_name > Policies.
- Click the name of the policy to modify.
- Under Additional Properties, select Preferred servers and select the preferred servers for this policy.
Click Add to move core group servers into the list of preferred servers.
Select specific servers in the list and click Move up and Move down to adjust the order of the servers within the list. Make sure that the most preferred server is at the beginning of the list and the least preferred server is at the end of the list.
- After you complete the preferred servers list, click OK.
- Click OK and then click Review.
- Select Synchronize changes with nodes, and then click Save.
ResultsAll work items for the messaging engine on the associated cluster are routed to the new preferred server.
Set up a high availability environment