The team of GitHub announced recently the release of their latest tool for the Git ecosystem.
It is called DGit (Distributed GIT), as they claim “a new distributed storage system that dramatically improves the availability, reliability, and performance of serving and storing Git content.”

As you might know, Git itself is distributed—any copy of a Git repository contains every file, branch, and commit in the project’s entire history. (this still amazes me every day :D) DGit uses this property of Git to keep three copies of every repository, on three different servers. The design of DGit keeps repositories fully available without interruption even if one of those servers goes down. Even in the extreme case that two copies of a repository become unavailable at the same time.

fileservers

More information : http://githubengineering.com/introducing-dgit/