Designing for Global Scale
Master multi-region active-active architecture, geo-routing and latency-based DNS, data sovereignty and compliance (GDPR), global load balancing with Anycast, cross-region replication patterns, conflict resolution strategies, and how companies like Cloudflare and Stripe operate globally.
Master multi-region active-active architecture, geo-routing and latency-based DNS, data sovereignty and compliance (GDPR), global load balancing with Anycast, cross-region replication patterns, conflict resolution strategies, and how companies like Cloudflare and Stripe operate globally. This hands-on tutorial focuses on practical implementation of designing for global scale concepts.
Designing for Global Scale
A system that works perfectly in US-East is not a global system — it's a system with a distant connection for everyone else. Global scale requires rethinking latency (London to Virginia = 70ms minimum), data sovereignty laws (GDPR: European data stays in Europe), and the fundamental challenge of keeping data in sync across continents.
[!IMPORTANT] The speed of light is non-negotiable. US-East to Singapore is ~200ms round trip, minimum, even on a direct fiber cable. Global systems must co-locate data and computation with users — not just add CDN. This means multi-region database deployments and regional API servers.
Latency Reality Check
Multi-Region Architecture Patterns
Global Database Options
| Database | Global Strategy | Consistency | Latency |
|---|---|---|---|
| Google Spanner | Active-Active, all regions | Strong (TrueTime) | 5-10ms intra-region |
| CockroachDB | Active-Active, multi-region | Configurable | 100-300ms cross-region |
| AWS Aurora Global | Active-Passive, 1 writer region | Strong (primary), eventual (secondary) | < 1s replication lag |
| DynamoDB Global Tables | Active-Active, all regions | Eventual | < 1s replication |
| Cassandra Multi-DC | Active-Active | Tunable (CL: LOCAL_QUORUM) | Custom per write |
Quiz
Quiz
Question 1 of 2Your app serves both US and Singapore users. The backend is only in US-East (Virginia). Singapore users report the app feels slow. The most impactful architectural change is:
Official Resources
- Google Spanner — Globally Distributed Database Paper
- AWS Global Infrastructure
- Cloudflare — Anycast Network
- GDPR Official Text
Key Takeaways
✅ Speed of light is the constraint — co-locate compute and data with users using multi-region deployment.
✅ Active-Passive = simple, lower latency for primary region only. Active-Active = low latency everywhere but needs conflict resolution.
✅ GDPR/data sovereignty forces regional data isolation — EU data must stay in EU databases.
✅ CRDTs are the best conflict resolution for specific data types (counters, sets) — mathematically proven correct.
✅ User-region affinity is the most practical approach for user data — route users to their home region consistently.
What's Next?
One final chapter to complete the course — practical interview strategy!
Next: Module 10 — Interview Strategy & Course Conclusion — How to approach system design interviews and what you've learned.