<i>Eric cited Cisco, with 15 terabytes in source control, and 50 developers writing perl scripts on top of ClearCase to serve 6000 users. That scale of problem is something the open source, distributed tools aren’t able to handle.</i><p>Obviously ClearCase can't handle it either if they need 50 developers to manage it. As much as I despise ClearCase, I don't think the tools, their development process, or implementation idiom are the problem here. Keeping 15TB of objects in a differential system is a <i>category error</i> (if more than a few % of that isn't generated or data they've got bigger problems).