Yes. Beginning with WebLogic Server version 6.0, EJBs must be homogeneously deployed across a cluster for the following reasons:
- To keep clustering EJBs simple
- To avoid cross server calls which results in more efficiency. If EJBs are not deployed on all servers, cross server calls are much more likely.
- To ensure that every EJB is available locally
- To ensure that all classes are loaded in an undeployable way