How Netflix Scales Global Video Streaming with AWS and Microservices

Overview

Netflix is the world’s leading subscription video‑streaming service, serving over 167 million subscribers in more than 200 countries and consuming more than 1.65 billion hours of video each day. Its engineering team spent over eight years building a highly available and scalable streaming system.

Infrastructure Migration

In August 2008, after a major DVD‑rental outage, Netflix decided to move its entire infrastructure from private data centers to the public cloud (AWS) and to replace monolithic applications with a micro‑service architecture.

Architecture

From a software‑architecture perspective, Netflix consists of three major parts: the client, the backend, and the content‑delivery network (CDN).

Client

The client runs on browsers, iOS, Android, smart TVs, and other devices. Netflix provides its own SDK to control playback, adapt to network conditions, and select the best Open Connect Appliance (OCA) server.

Backend

The backend runs entirely on AWS and includes compute (EC2), storage (S3), micro‑services, distributed databases (DynamoDB, Cassandra), big‑data processing (EMR, Hadoop, Spark, Flink, Kafka), and video transcoding tools.

Open Connect CDN

Open Connect is a global CDN composed of Open Connect Appliances (OCAs) deployed inside ISPs and IXPs. OCAs store large video files and stream them directly to users, reporting health and content status to a control‑plane service on AWS.

Playback Flow

When a user clicks Play, the client contacts the Playback service on AWS, which validates the request, consults the Steering service to obtain a list of healthy OCAs, and the client selects the optimal OCA for streaming.

Design Goals

High global availability of the streaming service.

Resilience to network failures and system outages.

Minimized latency across diverse network conditions.

Scalability to handle high request volumes.

Trade‑offs

Netflix trades consistency for lower latency and higher availability, using caches (EVCache) and eventually consistent stores (Cassandra) to serve requests quickly while tolerating stale data.

Resilience

Netflix employs chaos engineering, injecting random failures into production to test detection, isolation, and recovery mechanisms. Services such as Zuul (API gateway) provide adaptive retries and concurrency limits, while Hystrix isolates micro‑service failures.

Scalability

AWS Auto Scaling automatically adds or removes EC2 instances based on load. Netflix runs millions of containers on its open‑source Titus platform, enabling horizontal scaling across multiple regions. Parallel execution in network event loops and asynchronous I/O further improves throughput.

Conclusion

The Netflix streaming platform demonstrates a mature cloud‑native architecture that delivers high availability, low latency, strong scalability, and fault tolerance to millions of subscribers worldwide, making it a reference implementation for large‑scale production systems.