Design YouTube/Netflix - Scale and Constraints

User Scale

• Registered Users: 2B
• Daily Active Users: 500M (25%)
• Monthly Active Users: 1.5B (75%)
• Concurrent Viewers: 100M peak
• Channels: 50M active channels

Content Volume

• Total Videos: 500M videos
• Upload Rate: 500 hours per minute
• Daily Uploads: 720,000 hours per day
• Average Video: 10 minutes, 500MB
• Total Storage: 650PB (5 years)

Traffic Patterns

• Video Views: 1B per day (11,574 VPS)
• Peak Views: 35,000 VPS
• Watch Time: 1B hours per day
• Average Session: 40 minutes
• Read:Write Ratio: 1000:1

Bandwidth Requirements

Streaming:
- Views: 1B/day
- Duration: 10 min average
- Bitrate: 2 Mbps average
- Total: 1B × 10 × 2 Mbps = 20PB/day = 231TB/s
- With CDN (95% hit): Origin 11.6TB/s

Upload:
- 500 hours/min × 500MB/hour = 250GB/min = 4.2GB/s

Storage Estimates

Original Videos:
720K hours/day × 365 × 5 years × 2GB/hour = 2,628PB

Transcoded (4 resolutions):
2,628PB × 4 = 10,512PB

Thumbnails:
500M videos × 5 thumbnails × 100KB = 250TB

Total: ~10,762PB (with compression: ~8,000PB)

Performance Targets

• Playback Start: <2s p95
• Rebuffer Rate: <1%
• Upload Success: 99.9%
• Search Latency: <300ms p95
• CDN Hit Rate: >95%

Compute Resources

• Transcoding Workers: 100,000 GPU servers
• Application Servers: 50,000 servers
• Database Servers: 10,000 servers
• Cache Servers: 5,000 Redis nodes

Cost Estimates

Monthly:
- Compute: $50M
- Storage: $160M (8PB × $20/TB)
- CDN: $500M (231TB/s × 2.6PB/month × $80/TB)
- Transcoding: $100M
Total: ~$810M/month
Cost per DAU: $1.62/month

This scale analysis provides the foundation for YouTube/Netflix architecture.