Design a fault-tolerant Video Streaming System
Last updated: January 21, 2026
Quick Overview
Design a fault-tolerant video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
PlanetScale
January 21, 202612
11
4,280 solved
Design a fault-tolerant video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
PlanetScale asks this during the Technical Screen to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- What would the deployment pipeline look like for this system?
- How would you optimize costs as the system scales?
- What happens if one of your database nodes goes down?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Requirements
Functional Requirements
- Video Upload: Users can upload videos in various formats.
- Video Streaming: Users can stream videos with adaptive bitrate streaming.
- User Authentication...
Capacity Estimation
Assuming a user base of 10 million users with an average of 10 video requests per user per day:
- Total Requests per Day: 10M users * 10 requests = 100M requests/day.
- **Requests per Second (QPS)...
Submit Your Answer
