Set up a high availability environment

The high availability framework provided with the product eliminates single points of failure and provides peer to peer failover for applications and processes running within the product environment. This infrastructure is managed by a high availability manager and includes cells, clusters, core groups, and high availability groups. Every high availability group has a policy associated with it that the high availability manager uses to determine which members of a high availability group are active at a given time.

Plan out how we need to set up the high availability environment to avoid the risk of a failure without failover coverage. As part of the planning process, understand how the high availability manager can assist you in controlling this type of environment.

The high availability manager is designed to function in all of the supported product topologies. However, a high availability-managed environment must comply with the following rules:

• A cell in a high availability infrastructure is partitioned into one or more core groups. The product provides a default core group as part of the high availability manager function. We can use the console to create additional core groups.

• A core group cannot extend beyond the boundaries of a cell, and it cannot overlap with any other core groups.

• A cluster must be a member of only one core group. All of the individual members of that cluster must be members of the same core group.

• Individual application servers are also members of a core group.

• All running members of a core group must be able to communicate with all of the other running members of that same core group.

While administering the core groups, we might need to perform one or more of the following tasks. These tasks can be performed in any order.

1. Enable the high availability manager if it is not already enabled.
   

2. View information about the high availability groups, core groups, and core group members.

3. Create a new policy and associate it with a high availability group.
   

4. Change the policy that is associated with a high availability group.

5. Create a new core group.
   

6. Change the configuration settings for a core group.

   While running the applications in a highly available environment, you might want to move core group members to a different core group. You also might want to change one or more of the following:

   • The servers that designated as preferred coordinators.

   • The number of core group coordinators.

   • The settings for the discovery protocol, or the failure detection protocol. We might also want to change the version of the protocol.

   • (zos) Select an alternate protocol provider to use instead of the default Discovery Protocol and Failure Detection Protocol.

   • The replication settings for a core group.

7. Configure a transport for a core group.
   

   For an IIOP transport, you might also need to complete one or more of the following actions:

   • Configure core group IP caching.

   • Configure socket buffers for the core group.

8. Specify a core group when we add a node.
   

9. Specify a core group when creating an application server.
   

10. Set up a core group bridge.
    

    If we are using multiple core groups and members of different groups need to communicate with each other, set up a core group bridge to enable this communication.

11. (zos) Set up a sysplex that is highly available.
    

12. (zos) Control application rollout and workload routing in a high availability configuration.

13. (zos) Manually update a high availability application.
    

What to do next

After setting up the product environment to comply with all of the high availability-managed environment rules, use the default core group to control this environment.

Avoid trouble: Do not add core groups unless we cannot properly perform without them. Also, do not change the default configurations unless doing so provides the solution to a specific problem. When you do make configuration changes, such as changing the policy for a high availability group or moving core group members between core groups, make sure you fully understand the effect such changes have on the entire environment. Such changes might affect application processing.gotcha

Read the topic High availability environment troubleshooting tips if you encounter problems while running applications in the high availability environment.

Related concepts

High availability manager

(zos) Application update procedure in a high availability environment

Related tasks

Set up IP addresses for high availability manager communications

Specify a preferred server for messaging requests

(zos) Automatically rolling out updates to a high availability application