Compare this approach with Google's - github sticks to the git-compatible 'loose' repository format on vanilla filestorage, while google uses packs on top of their BigTable infrastructure, and requires changes to repo-access at the git-level [1].
[1] https://www.eclipsecon.org/2013/sites/eclipsecon.org.2013/fi...
Interesting how Github is sounding like Google and Amazon. They're probably hitting the scale where it makes sense to build internal APIs and infrastructure abstractions to support their operations, eg. Bigtable and S3. In fact, DGit sounds like another storage abstraction like Bigtable and S3, albeit limited - eg. a git repo must be stored fully on a single server (based on my cursory reading of github's description of DGit), but in Bigtable, data is split into tablets that comprise the table might be stored on different places, which would allow higher utilization of resources.