A distributed session can run in multiple Sun Java System Application Server instances, if:
Each server instance has access to the same high-availability database (HADB). For information about how to enable this database, see configure-ha-cluster(1).
Each server instance has the same distributable web application deployed to it. The web-app element of the web.xml deployment descriptor file must contain the distributable element.
The web application uses high-availability session persistence. If a non-distributable web application is configured to use high-availability session persistence, the server writes an error to the log file.