Design a crash-resilient file system

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?