The goal of migration is to reconstruct your earlier version of WebSphere Application Server in a nearly identical Version 6.1 environment. One goal of coexistence is to create a mixed-version environment that is not in conflict and allows the nodes of all versions to start and run at the same time; another goal is to create an environment that facilitates rollback and allows one or the other version to run at one time. Interoperating is exchanging data between two coexisting product installations or between products on different systems.
WebSphere Application Server Version 6.1 can coexist with Version 5.x and Version 6.0.x. Depending on the previous version of WebSphere Application Server, there might be port conflicts that need to be resolved. See Coexistence support and Configuring ports for more information.
WebSphere Application Server Version 6.1 migration leverages the existing configuration and applications and changes them to be compatible with the WebSphere Application Server Version 6.1 environment. Existing application components and configuration settings are applied to the Version 6.1 environment during the migration process.
If you use an earlier version of WebSphere Application Server, the system administrator might have fine-tuned various application and server settings for your environment. It is important to have a strategy for migrating these settings with maximum efficiency and minimal loss.
You can perform incremental migration of your WebSphere Application Server Version 5.x or 6.0.x configuration by calling the migration tools multiple times, each time specifying a different set of instances or profiles.
The migration tools migrate applications and configuration information to the new version as described in Migrating product configurations. See Using the migration tools to migrate product configurations.
If you neither migrate nor coexist with an earlier version of WebSphere Application Server, you are choosing to ignore the previous installation and you can run only one version at a time because of conflicting default port assignments. It is possible for both versions to run at the same time without conflict if you use non-default ports in the earlier version. To set up coexistence with WebSphere Application Server Version 5.x or 6.0.x, ensure that unique ports are selected during profile creation for the Version 6.1 installation. To set up coexistence with an existing installation of Version 6.1, select the radio button that states "Install a new copy of the V61 Application Server product" during installation.
You can resolve conflicting port assignments by specifying port assignments for coexistence during profile creation, by wsadmin scripting or by using the Servers > Application Servers > server1 > Ports administrative console page to ensure that WebSphere Application Server Version 6.1 can run with an earlier version.
See Wsadmin tool.
See Port number settings in WebSphere Application Server versions for more information.