An article comprising a substrate and a plurality of coating units disposed over the substrate is provided. Each coating unit comprises an oxygen-getter layer and a barrier layer. Embodiments of the present invention introduce redundancy to enhance the robustness of a coating system. Multiple protective coating units are disposed over a substrate so that failure of one of the coating units will be far less likely to subject the substrate to direct risk of exposure to the environment. Failure of an outer coating unit merely exposes a pristine protective coating unit, rather than the substrate or a less protective coating layer. In this way, embodiments of the present invention drastically reduce reliance on the performance of one particular coating layer, promoting a more robust and reliable system.