Design Caching Infrastructure for IoT devices
Last updated: December 3, 2025
Quick Overview
Design a high-throughput caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
xAI
December 3, 202543
7
320 solved
Design a high-throughput caching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at xAI typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
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
- How would you handle schema migrations with zero downtime?
- How would you handle a region-wide outage?
- How do you ensure data consistency across multiple services?
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Requirements
Functional Requirements
- Data Retrieval: The caching system must enable IoT devices to quickly retrieve frequently accessed data.
- Data Storage: Support for temporary storage of statef...
Capacity Estimation
Assuming xAI expects to support 1 million active IoT devices with an average of 100 requests per minute:
- Total Requests: 1,000,000 devices * 100 requests/device/minute = 100,000,000 requests/mi...
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