Design a crash-resilient file system
Company: Netflix
Role: Software Engineer
Category: System Design
Difficulty: easy
Interview Round: Technical Screen
## Prompt
Design a **resilient file system** that can **recover file contents correctly after a system crash** (e.g., power loss / kernel panic). The interviewer gives a broad prompt (no coding required) and expects you to propose a production-ready design and discuss bottlenecks and improvements.
### Requirements
- Support basic operations: `create`, `read`, `write/append`, `delete`, `rename`.
- After a crash at any moment, the system must be able to **recover to a consistent state** such that:
- File contents are not corrupted.
- Metadata is consistent (directory entries, inode/metadata, free-space tracking).
- Define the durability guarantee you target (e.g., after `fsync`/close, data must survive).
### Non-functional considerations
- Performance (throughput/latency) under heavy writes.
- Space overhead.
- Operational concerns for “production”: observability, upgrades, capacity growth.
### Follow-ups (discuss explicitly)
- Where are the bottlenecks in your design?
- What changes would you make to ship this to production at scale?
Quick Answer: This question evaluates understanding of durable storage and crash recovery mechanisms in file system design, including metadata consistency, durability guarantees, and operational concerns like performance and space overhead.