GitHub, the Microsoft-owned code hosting service, rebuilt how it stores Git repositories so that many AI coding agents can write to the same repository at once. Traffic to one repository grew about 4x between March and May 2026, from 44 million to 181 million requests per day. The new design keeps Git data in Azure Blob Storage, Microsoft's cloud file store. It moves references, the pointers that name branches and commits, into a new replicated log service called Ref-CAS. In internal tests, the company says, 5,000 concurrent agents sent 7,200 pushes per second to one repository.
Two earlier designs failed. A single log file for all references allowed only one write at a time and reached only a few hundred writes per second. Splitting references across several files sped up writes but slowed reads, which "outnumber writes by orders of magnitude." The post gives no cost figures.
