Introduction to System Design: Key Concepts and Architecture Patterns

📌 What is System Design?

System design is the process of defining the architecture, components, modules, interfaces, and data flow for a system to meet specific requirements. It is a crucial skill for building scalable, reliable, and maintainable systems.

🧩 Key Concepts in System Design

1. Scalability

The ability of a system to handle a growing amount of work.

• Vertical Scaling (Scaling Up): Adding more power (CPU, RAM) to an existing machine.

• Horizontal Scaling (Scaling Out): Adding more machines (nodes) to distribute the load.

  
  

Example: Facebook uses horizontal scaling to handle billions of users.

2. Load Balancing

Distributes incoming traffic across multiple servers to ensure no single server is overwhelmed.

• Types of Load Balancers: Hardware, Software, and DNS-based.

• Common Algorithms: Round Robin, Least Connections, IP Hashing.

  
  

Tip: Use multiple load balancers to prevent a single point of failure.

3. Caching

Stores frequently accessed data to reduce load times.

• Types: Client-side, Server-side, CDN (Content Delivery Network)

• Tools: Redis, Memcached

  
  

Example: YouTube uses caching to quickly load videos.

4. Database Management

• Relational Databases (SQL): Structured data with relationships (e.g., MySQL, PostgreSQL)

• NoSQL Databases: Unstructured data with high scalability (e.g., MongoDB, Cassandra)

• Sharding: Splitting databases to improve performance.

  
  

Learning: Choose SQL for consistency, NoSQL for flexibility.

5. Microservices Architecture

An architectural style where a system is divided into small, independent services.

• Pros: Scalability, fault isolation.

• Cons: Complex communication, monitoring challenges.

  
  

Example: Netflix uses a microservices architecture to stream videos seamlessly.

6. Message Queues

Allows asynchronous communication between services.

• Tools: RabbitMQ, Apache Kafka

• Use Case: Order processing systems in e-commerce.

📐 Common Architecture Patterns

1. Layered (N-Tier) Architecture

• Layers: Presentation, Business Logic, Data Access, Database

• Use Case: Web applications

2. Client-Server Architecture

• Client: Sends requests

• Server: Processes requests and sends responses

• Use Case: Websites, chat applications

3. Peer-to-Peer (P2P) Architecture

• Decentralized communication model

• Use Case: File-sharing applications like BitTorrent

4. Event-Driven Architecture

• Components: Event producers and consumers

• Use Case: Real-time notifications (e.g., WhatsApp message alerts)

5. Serverless Architecture

• Uses cloud services to execute code without managing servers.

• Use Case: Image processing, real-time file uploads

💡 Tips for Designing Systems

1. Clarify Requirements: Ask about scale, users, and performance needs.

2. Use Diagrams: Visualize components with architecture diagrams.

3. Focus on Bottlenecks: Identify and resolve points that may slow the system.

4. Ensure Redundancy: Prevent single points of failure.

5. Plan for Monitoring: Add logs and alerts for performance tracking.

📝 Interview Tips for System Design Rounds

• Structure Your Answer: Use the STAR method (Situation, Task, Action, Result).

• Discuss Trade-offs: Explain why you chose one solution over another.

• Handle Scaling: Always address how your design scales.

• Use Common Patterns: Mention standard architecture patterns.

• Think Security: Address data protection and privacy.

Common Interview Prompts:

• Design a URL shortener (like Bit.ly)

• Design a social media feed system (like Twitter)

• Design a file storage service (like Dropbox)

🚀 Conclusion

Mastering system design requires practice, a deep understanding of architecture patterns, and the ability to communicate ideas clearly. Focus on key components, prepare for trade-offs, and always design for scalability and reliability.