Design a fault-tolerant Logging System
Last updated: March 15, 2026
Quick Overview
Design a fault-tolerant logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
SentinelOne
March 15, 20260
12
3,762 solved
Design a fault-tolerant logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at SentinelOne 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
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
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 do you ensure data consistency across multiple services?
- How would you optimize costs as the system scales?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements:
- Log Ingestion: The system should accept log entries from millions of devices in real-time.
- Log Retrieval: Users should be able to retrieve logs based on vari...
Capacity Estimation
Assuming SentinelOne manages approximately 10 million devices worldwide, with each device generating an average of 1 log per second:
- Total Logs per Second: 10 million logs/sec
- **Storage Requir...