Planning Your Commerce Server Site Migration
The effort involved in migrating your Web sites to Microsoft Commerce Server 2009 R2 depends on which version of the product you are migrating from. Planning for migration involves learning which resources can be upgraded and which are no longer supported, knowing what data will be modified, and learning about the tools that are available to help you.
Mixed deployments that consist of Commerce Server 2009 R2 and earlier versions of Commerce Server are not supported. All servers in a Web farm must use the same version of Commerce Server.