There are many security options that can be used in a cluster. All of the VMM federated security options, including multiple LDAP repositories, database repositories, and the default file-based repository can be used. Additionally there is an option to use standalone LDAP security instead of the VMM federated security approach.
Note: It is not recommended to use the file-based repository in a production environment. The reason is that updates are only possible through the WebSphere Application Server administrative console, not through portal user management. These updates are sent to each node in the cell using deployment manager file synchronization. This can be time consuming for large volumes of users and groups. Also, synchronization does not occur at the same time for all nodes in a cell, so there will be time windows when the nodes in the cell have differing security definitions.