Essential Patterns for Building Scalable and Available Systems
Learn systematic approaches to designing fault-tolerant architectures that scale gracefully and ensure consistent uptime in production environments.
Understanding how to design for scalability and availability is a core skill for any software engineer and a fundamental part of effective System Design.
This skill demonstrates an understanding of how to build resilient systems that maintain performance and reliability as demands grow. The patterns and strategies chosen during a system’s foundation directly determine whether it can scale gracefully or collapse when it matters most.
This lesson provides a practical framework for building scalable and highly available systems.
We start by exploring foundational scaling patterns, then progress through advanced migration strategies, availability mechanisms, and essential traffic management components. Let’s begin by exploring how these pillars, scalability and availability, work together to create systems that users can depend on.
Scalability patterns in System Design
As discussed earlier in this course, scalability refers to a system’s ability to handle an increasing amount of work by adding resources as needed.
Think of it as designing a building with a foundation strong enough to support extra floors later. In System Design, these factors may include user traffic, data volume, or transaction frequency. A scalable system can accommodate this growth efficiently without degrading performance.
The primary methods for achieving scalability are through
Educative byte: For many modern cloud-native applications, horizontal scaling is preferred because it offers greater elasticity and avoids the single point of failure and physical limits inherent in vertical scaling.
To manage the complexity that comes with the horizontal scaling of systems, architects rely on specific design patterns. We will explore the following three patterns that address common challenges in distributed systems:
The Strangler fig pattern for migrating legacy systems.
The Saga pattern for managing distributed transactions.
The Sidecar pattern for extending service functionality.
These scaling fundamentals set the stage for more complex patterns that enable systems to evolve and operate reliably at scale. Next, we will examine how to safely modernize a monolithic application.
Strangler fig pattern
Imagine a city deciding to replace its old, crumbling road network.
Instead of shutting down the entire city, they build new roads alongside the old ones, gradually diverting traffic until the old system is no longer needed and can be safely demolished. This is the essence of the strangler fig pattern.
Named after a fig vine that envelops and eventually strangles its host tree, this pattern enables a gradual and safe migration from a legacy monolithic application to a modern microservices architecture.
The process involves placing a facade or proxy in front of the monolith.
This facade intercepts incoming requests, routing them either to the old monolithic code or to a newly built microservice. Over time, more functionality is carved out of the monolith and replaced with new ...