GitHub Project Rubicon: New Git Storage Hits ~5,000 Concurrent Agents and ~7,200 Pushes/sec in Internal Tests
On 2026-11-05 GitHub Engineering detailed the next-gen Git storage announced at Universe (codename Rubicon). Vendor internal tests: ~5,000 concurrent agents and ~7,200 pushes/sec on one repo with low-latency reads. Objects live in Azure Blob; reference updates go through Ref-CAS; disposable virtual replicas serve compute. Limited private preview; broader rollout early next year.

Key Takeaways
- Source: GitHub Blog Inside GitHub's new Git storage architecture (2026-11-05) + @github; prior series Building… and The bridge…
- Scale (vendor internal tests): ~5,000 concurrent agents and ~7,200 pushes/sec on one repo with low-latency reads
- Architecture: objects/packs in Azure Blob; refs + pack manifest in Ref-CAS; virtual replicas scale out; compaction/GC on separate nodes
- Principles: coordinate only reference updates; decouple storage from compute so adding read capacity does not slow writes
- Availability: limited private preview; broader rollout early 2027; Git workflows unchanged for developers







