How to approach system design round?

How to Approach a System Design Round

System design interviews evaluate your ability to design scalable, efficient, and reliable systems while showcasing your problem-solving and communication skills. Here’s a step-by-step guide to excel:

1. Understand the Problem

• Ask Clarifying Questions:
  • What are the main use cases and requirements?
  • Are there any constraints like latency, scalability, or cost?
  • What is the expected scale (e.g., number of users, requests per second)?
• Why It’s Important: Clear requirements help you avoid assumptions and address the right challenges.

2. Define Functional and Non-Functional Requirements

• Functional: What the system should do (e.g., store data, retrieve information).
  • Example: "The system should allow users to upload and share photos."
• Non-Functional: How the system should perform.
  • Examples: Scalability, reliability, performance, security, and maintainability.

3. Outline the High-Level Architecture

• Key Components:
  • Load Balancers
  • Databases (SQL/NoSQL)
  • Caching Layer (Redis/Memcached)
  • Storage (S3 or block storage)
  • APIs and Web Servers
• Example: "To handle high traffic, we’ll use a load balancer to distribute requests across multiple application servers. A caching layer will reduce database load."

4. Drill Down into Details

• For each component, explain:
  • Purpose: What role it plays.
  • Choices: Why you picked it (e.g., NoSQL for scalability or Redis for low-latency caching).
  • Implementation: How it works (e.g., partitioning, replication, or sharding).

5. Discuss Trade-Offs

• Explain Alternatives: Acknowledge other design options and why you didn’t choose them.
• Highlight Trade-Offs:
  • Example: "A SQL database offers strong consistency, but NoSQL provides better horizontal scalability, which we need for this use case."