We are a big believer in browser testing on the real devices, thus we offer real iPhones, iPads, and Android devices - not just simulators. Hosting these in a traditional server rack, however, is a challenge. As we have grown, we have evolved our techniques. We started out with dish racks. Yes, dish racks. Sitting on shelves in our 42U racks. Dish racks held the devices separate, similarly to the way it holds plates apart so they can dry, and worked pretty well for tablets (not so great for phones). You could put around 15 to 25 devices in a given shelf, and 4 shelves in a cabinet.