Hercules Distributed File System

I haven't run my own benchmarks yet, as I am still fixing bugs and reviewing my decisions, but it works overall. The documentation was done via LLM, so I will be editing it poco a poco

A production-grade implementation of the Google File System (GFS) in Go

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📚 Table of Contents

• Overview
• Features
• Quick Start
• Architecture
• Documentation
• Usage Examples
• Development
• Contributing
• License

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Overview

Hercules is a distributed file system that faithfully implements the Google File System (GFS) design described in the seminal 2003 paper. Built entirely in Go, it provides a scalable, fault-tolerant storage solution for large-scale data with focus on high throughput and availability.

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Why Hercules?

• Production-Ready: Comprehensive implementation with RPC, HTTP gateway, and client SDK
• Fault Tolerant: Automatic replication, failure detection using φ Accrual algorithm, and self-healing
• Scalable: Designed to handle petabytes of data across thousands of machines
• Well-Documented: Extensive documentation covering architecture, APIs, and deployment
• Docker-First: Full Docker Compose setup for easy deployment and development

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Features

✅ Core GFS Features

• 64MB chunk-based storage with configurable size
• Triple replication (configurable) for data redundancy
• Single master architecture for simplified coordination
• Lease-based mutation protocol for consistency

✅ Advanced Capabilities

• φ Accrual Failure Detection: Probabilistic failure detection using network heartbeats
• HTTP Gateway: RESTful API for file operations
• Go Client SDK: Native Go client library
• Archive Manager: Snapshot and archival support
• Real-time Monitoring: System metrics and visualization

✅ Production Features

• Docker and Docker Compose deployment
• Persistent metadata and chunk storage
• Graceful shutdown and recovery
• Comprehensive logging and error handling
• Health checks and liveness probes

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Quick Start

Using Docker (Recommended)

# Clone the repository
git clone https://github.com/caleberi/hercules-dfs.git
cd hercules-dfs

# Start all services (master, 3 chunkservers, gateway, redis)
docker-compose up -d

# Verify services are running
docker-compose ps

# View logs
docker-compose logs -f

Services will be available at:

• Master Server: localhost:9090
• Chunkserver 1: localhost:8081
• Chunkserver 2: localhost:8082
• Chunkserver 3: localhost:8083
• Gateway API: http://localhost:8089
• Redis: localhost:6379

Using Make

# Build all Docker images
make build-all

# Start services
make up

# Check status
make status

# View logs
make logs

# Stop services
make down

Manual Setup

# Install dependencies
go mod download

# Terminal 1: Start Master
go run main.go -ServerType master_server -serverAddr 127.0.0.1:9090 -rootDir ./data/master

# Terminal 2-4: Start Chunkservers
go run main.go -ServerType chunk_server -serverAddr 127.0.0.1:8081 -masterAddr 127.0.0.1:9090 -rootDir ./data/chunk1
go run main.go -ServerType chunk_server -serverAddr 127.0.0.1:8082 -masterAddr 127.0.0.1:9090 -rootDir ./data/chunk2
go run main.go -ServerType chunk_server -serverAddr 127.0.0.1:8083 -masterAddr 127.0.0.1:9090 -rootDir ./data/chunk3

# Terminal 5: Start Gateway
go run main.go -ServerType gateway_server -gatewayAddr 8089 -masterAddr 127.0.0.1:9090

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Architecture

Hercules follows the GFS master-chunkserver architecture:

┌─────────────┐
│   Clients   │
│  (Gateway)  │
└──────┬──────┘
       │ ① Request metadata
       ▼
┌─────────────────┐
│  Master Server  │◄──────┐
│   (Metadata)    │       │ Heartbeats
└─────────────────┘       │
       │ ② Return chunk   │
       │    locations     │
       ▼                  │
┌───────────────────────────────┐
│     Chunkserver Network       │
│  ┌────────┐  ┌────────┐  ┌───┤
│  │Chunk 1 │  │Chunk 2 │  │...│
│  └────────┘  └────────┘  └───┘
└───────────────────────────────┘
       │ ③ Read/Write data
       ▼
   [Client]

Components

Component	Description	Port
Master Server	Manages metadata, namespace, chunk placement	9090
Chunkservers	Store 64MB chunks, handle read/write	8081-8083
Gateway	HTTP API for file operations	8089
Failure Detector	Monitors server health (φ Accrual)	-
Redis	Backend for failure detection data	6379

For detailed architecture, see Architecture Documentation.

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Documentation

📖 Complete Documentation

All documentation is in the docs/ directory:

Getting Started

• Complete Documentation Index
• Configuration Reference
• Development Guide

Architecture

• System Overview - High-level design and principles
• Component Deep Dives (coming soon)

API Reference

• Master Server API - RPC methods for metadata operations
• Chunk Server API - RPC methods for data operations
• Gateway HTTP API - REST endpoints

Deployment

• Docker Deployment - Deploy with Docker Compose
• Local Development Setup (coming soon)
• Production Deployment (coming soon)

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Usage Examples

HTTP API (via Gateway)

# Create a file
curl -X POST http://localhost:8089/api/v1/files \
  -H "Content-Type: application/json" \
  -d '{"path": "/myfile.txt"}'

# Upload a file
curl -X POST http://localhost:8089/api/v1/files/upload \
  -F "file=@localfile.txt" \
  -F "path=/remote/file.txt"

# Download a file
curl -X GET "http://localhost:8089/api/v1/files/download?path=/remote/file.txt" \
  -o downloaded.txt

# List directory
curl -X GET "http://localhost:8089/api/v1/directories?path=/"

# Get system status
curl -X GET http://localhost:8089/api/v1/system/status | jq

Go SDK

import "github.com/caleberi/distributed-system/hercules"

// Create client
client := hercules.NewHerculesClient("127.0.0.1:9090")

// Create file
err := client.CreateFile("/myfile.txt")

// Write data
data := []byte("Hello, Hercules!")
err = client.Write("/myfile.txt", 0, data)

// Read data
readData, err := client.Read("/myfile.txt", 0, len(data))

// List directory
files, err := client.List("/")

See API Documentation for complete reference.

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Development`

Development

Prerequisites

• Go 1.18+
• Docker & Docker Compose (for containerized development)
• Redis (for failure detection)
• Make (optional, for build automation)

Local Development Setup

# Clone repository
git clone https://github.com/caleberi/hercules-dfs.git
cd hercules-dfs

# Install dependencies
go mod download

# Run tests
go test ./...

# Run with hot reload (using air or similar)
# See docs/guides/development.md for detailed setup

Running Tests

# Unit tests
go test ./...

# With coverage
go test -cover ./...

# Integration tests
python dtest.py

# Benchmarks
go test -bench=. ./...

Project Structure

hercules/
├── main.go              # Entry point
├── master_server/       # Master server implementation
├── chunkserver/         # Chunkserver implementation
├── gateway/             # HTTP gateway
├── hercules/            # Client SDK
├── failure_detector/    # Failure detection (φ Accrual)
├── namespace_manager/   # Directory/file management
├── common/              # Shared types and constants
├── rpc_struct/          # RPC definitions
├── docs/                # Documentation
└── example/             # Example applications

See Development Guide for detailed information.

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Contributing

We welcome contributions! Here's how you can help:

• 🐛 Report Bugs: Open an issue with detailed reproduction steps
• 💡 Suggest Features: Share your ideas for improvements
• 📝 Improve Documentation: Help make our docs even better
• 🔧 Submit Pull Requests: Fix bugs or implement new features

Contribution Guidelines

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes with clear commit messages
4. Add tests for new functionality
5. Ensure all tests pass (go test ./...)
6. Submit a Pull Request

For detailed guidelines, see CONTRIBUTING.md.

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Performance & Benchmarks

Hercules is designed for high throughput:

• Write Throughput: ~500 MB/s per chunkserver
• Read Throughput: ~800 MB/s (direct from chunkserver)
• Concurrent Appends: Thousands per second
• Metadata Ops: ~10,000 ops/sec (master)

Benchmarks run on standard commodity hardware (4 cores, 8GB RAM, SSD)

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Use Cases

Hercules is ideal for:

• Data Lakes: Store massive amounts of unstructured data
• Log Aggregation: Collect and store logs from distributed systems
• Media Storage: Store large media files with high availability
• Backup Systems: Reliable backup storage with replication
• Research: Study distributed file systems and fault tolerance

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Roadmap

• Core GFS implementation (master, chunkservers, client)
• Docker deployment
• HTTP Gateway
• φ Accrual failure detection
• Comprehensive documentation
• Multi-master support for high availability
• Encryption at rest and in transit
• Erasure coding for storage efficiency
• Kubernetes deployment manifests
• Web UI for administration
• S3-compatible API

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FAQ

Q: Is this production-ready?
A: Hercules is feature-complete and stable, but has not been battle-tested at Google scale. Use with appropriate testing for your use case.

Q: How does this compare to HDFS?
A: Similar design principles, but Hercules focuses on the original GFS design while HDFS has evolved with additional features.

Q: Can I use this for small files?
A: Yes, but 64MB chunks may waste space. Consider adjusting chunk size in configuration.

Q: What about POSIX compatibility?
A: Hercules does not aim for full POSIX compatibility, similar to GFS. It's optimized for append operations and large files.

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Resources

Papers & References

• The Google File System (2003) - Original GFS paper
• φ Accrual Failure Detection - Failure detection algorithm

Related Projects

• HDFS - Hadoop Distributed File System
• Ceph - Modern distributed storage
• MinIO - S3-compatible object storage

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Acknowledgements

This project is inspired by the groundbreaking work of:

The Google File System
Sanjay Ghemawat, Howard Gobioff, and Shun-Tak Leung
ACM SIGOPS Operating Systems Review, 37(5), 2003

Special thanks to:

• All contributors to this project
• The Go community for excellent tools and libraries
• The distributed systems research community

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Support

• 📧 Email: Create an issue on GitHub
• 💬 Discussions: GitHub Discussions
• 🐛 Bug Reports: GitHub Issues
• 📖 Documentation: docs/

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Built with ❤️ using Go

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