The goal of migration is to reconstruct your earlier version of WebSphere Application Server in a nearly identical V6.1 environment.
A 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.
WAS V6.1 can coexist with V5.x and V6.0.x. Depending on the previous version of WAS, there might be port conflicts that need to be resolved.
To migrate...
WAS V6.1 migration leverages the existing configuration and applications and changes them to be compatible with the WAS V6.1 environment. Existing application components and configuration settings are applied to the V6.1 environment during the migration process.
If you use an earlier version of WAS, 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 WAS V5.x or 6.0.x configuration by calling the migration tools multiple times, each time specifying a different set of instances or profiles.
See also:
If you neither migrate nor coexist with an earlier version of WAS, 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 WAS V5.x or 6.0.x, ensure that unique ports are selected during profile creation for the V6.1 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 console page...
Servers | Application Servers | server1 | Ports
...administrative console page to ensure that WAS V6.1 can run with an earlier version.
Coexistence processing changes the following configuration files:
Consider these issues in a migration or coexistence scenario:
Follow the procedure in Migrating Web server configurations to learn how to configure a Web server for sharing between WAS versions.