In this paper, we present a metamodel for specifying redundable software and hardware architectures. This metamodel takes into account the constraints on the number of redundant elements, the number of allowed failures, the execution times and allocation constraints. From such a specification, we generate all possible structural configurations. Then, we check that each of these configurations can be scheduled. This has been implemented as a tool chain relying on Alloy, SynDEx, and model transformations in Eclipse/EMF. This work allows system architects to explore different hardware and software architectures to implement different redundancy policies. It has been applied on a simple case study from the Ariane V launcher.