The default value of the force option for deployment is false in GlassFish Server 3.0.1. This default value was true in GlassFish Server v2. In GlassFish Server 3.0.1 you must explicitly set the option to true for redeployment. This option is not automatically set during the upgrade process. The purpose of this change is to avoid accidentally overwriting the contents of an existing application. This applies to both the Administration Console and command-line utility.
The asadmin redeploy command is also new in GlassFish Server 3.0.1 and offers an equivalent to --force=true. The force option is only applicable to the deploy command (command-line interface) and the deploy screen (console), not to the redeploy command and redeploy screen.