Planning to migrate a high-availability domain

This topic explains how to plan to migrate a high-availability domain.

High availability is the requirement for a system to be running all, or for a very high proportion of, the time. Providing a high-availability environment involves having multiple brokers so that some brokers can be used for backup purposes. The entire production domain might be duplicated so that the backup system can be switched on in the event of a problem.

Migrating in a high-availability environment presents a problem because there is a vulnerable period between stopping the previous version of the product and installing and starting WebSphere Message Broker Version 6.0. One solution is to install and configure WebSphere Message Broker Version 6.0 while the previous version of the product is running in parallel, and then switch to WebSphere Message Broker Version 6.0. Install WebSphere Message Broker Version 6.0 on either the same computers that are running the previous version of the product, or on a different set of computers.

The following sections of this topic provide a general framework for how you might want to migrate your high-availability domain. You might need to adjust these instructions to suit your specific circumstances. Refer to the product-specific migration topics for detailed migration instructions.

Preparing to migrate a high-availability domain

To achieve high-availability migration, your environment must be configured correctly. Complete the following tasks (production and test domains are described in Planning to migrate multiple domains):
  1. Ensure that the production domain that is to be migrated is configured for high availability. You must have at least three brokers supporting the executing applications, so that when broker 1 is being migrated, brokers 2 and 3 can provide backup support for each other. This is a standard setup for a high-availability domain at all times, and is not specific to migration.
  2. Ensure that the test domain is identical to the production domain. This means that you can identify any problems during the migration of the test domain and resolve them before you migrate the production domain.

Preparing to migrate the test domain

By migrating the test domain, you can ensure that operation is successful after migration and solve any problems before migrating the production domain. In message flow and message set development, each developer is often responsible for a particular area of functionality. Test the migration of your resources to WebSphere Message Broker Version 6.0 for each functional area in turn. The following steps describe one way in which to migrate the test domain to minimize disruption. Refer to the product-specific migration topics for detailed migration instructions.
  1. After you have backed up your resources and installed Version 6.0, create a Version 6.0 Configuration Manager and broker on as many computers as needed to mirror the production domain.
  2. Move one functional area to Version 6.0 by migrating the Message Brokers Toolkit and the resources that are used by the developer who is responsible for that area. Test that the migrated resources work as required by deploying them and checking the results. Resolve any problems, then migrate the remaining functional areas. Migrating the functional areas one by one means that existing development can continue on the previous version of the product.
  3. In the same way that you migrate the functional areas individually, migrate the previous version's brokers individually to Version 6.0. When you have migrated one broker, test that your resources still work as required by deploying the migrated resources for which this broker is responsible. Resolve any problems and repeat for the remaining brokers. Migrating the brokers one at a time means that only small changes are made at each stage. If problems occur, other brokers that have not been migrated yet can process requests while the migration problems are resolved.

Preparing to migrate the production domain

After you have migrated the test domain and resolved any problems, prepare to migrate the production domain. Before you migrate your resources, configure an administration system with the Version 6.0 Message Brokers Toolkit. This allows you to administer the new Version 6.0 components. Refer to the product-specific migration topics for detailed migration instructions.

When you are ready to perform migration, back up your resources.