Katkat
Back

Design a Distributed File System

DatabricksBackend Engineer · Technical Screen
MediumBackend EngineerTechnical ScreenSystem Design

Last updated

This question tests the ability to design a scalable, fault-tolerant distributed file system by addressing challenges in metadata management, data chunking, and cluster availability.

Problem Statement

Design a distributed file system that can store petabytes of data across thousands of commodity servers. The system must support high-throughput access for large files and provide strong consistency for file operations.

Functional Requirements

  • write(file_path, data): Store a file in the system.
  • read(file_path): Retrieve a file.
  • delete(file_path): Remove a file.
  • Support for large file sizes (e.g., up to several terabytes per file).

Non-Functional Requirements

  • Scalability: The system should handle millions of files and concurrent read/write operations.
  • Fault Tolerance: The system must remain available and data must be durable even if individual nodes fail.
  • Consistency: Once a write is acknowledged, subsequent reads should see the updated data.

Design Considerations

  • How do you handle metadata versus actual file content?
  • How do you partition data to ensure load balancing?
  • How do you handle node failure and data recovery?
  • What consistency model will you implement, and how does it affect performance?

Hints

Hint 1

Consider separating the control plane (metadata management) from the data plane (block storage).

Hint 2

Think about breaking files into fixed-size chunks and distributing these chunks across multiple storage nodes to maximize throughput.

Hint 3

Address the single point of failure risk inherent in a centralized metadata server by discussing replication or consensus protocols like Paxos or Raft.

Follow-up questions

  • How would you modify your design if the system requires low-latency access for many small files instead of large files?
  • What strategies would you implement to detect and repair data corruption or missing blocks in the background?
  • How would you handle client-side caching to reduce the load on your metadata service?