To design a distributed file system, I'd start by clarifying key requirements such as supported operations (CRUD, permissions, directory traversal), expected file sizes, read/write patterns, and scale (users, storage). Assuming standard operations, moderate file sizes (1MB-1GB), a read-heavy workload, and a large user base (e.g., 10 million), I would then consider the core components:
- Metadata Service: Manages file and directory information (names, sizes, locations, permissions). This needs to be highly available and consistent. Options include a distributed key-value store (like etcd or ZooKeeper) or a custom-built, replicated database.
- Data Storage Nodes: Stores the actual file content. Files would be chunked and distributed across these nodes for scalability and fault tolerance. Erasure coding or replication would be used for durability.
- Client Library/API: Provides an interface for applications to interact with the file system, abstracting away the distributed nature.
- Load Balancer/Gateway: Distributes client requests to appropriate metadata or data nodes.
Key design considerations would include:
- Consistency Model: How to handle concurrent updates (e.g., strong consistency for metadata, eventual consistency for data if acceptable).
- Scalability: Horizontal scaling of both metadata and data nodes.
- Availability & Fault Tolerance: Replication, erasure coding, and automatic node failure detection/recovery.
- Performance: Caching at the client and server levels, efficient data distribution, and optimized metadata lookups.
- Security: Authentication and authorization mechanisms.
Databricks
Google