The Trio : Scale, Fault Tolerance, Availability

The Three Questions Every Component Must Answer

Scale → Fault Tolerance → Availability

Scale: "What happens when we grow?"

Your tweet service works perfectly for 1,000 users. But reality hits different when you have 100,000 users, then 10 million, then 100 million people all tweeting at once. Can your system handle the growth without falling apart?

Fault Tolerance: "What happens when things break?"

Servers crash at 2 AM. Authentication fails during peak hours. Network cables get cut.

Hard drives die with precious user data. Your system needs to survive these disasters gracefully.

Availability: "How do we keep the lights on?"

Users expect 99.9% uptime - that's only 8.76 hours of downtime allowed per year.

Every minute your system is down equals lost revenue and frustrated users.

How do you serve millions when half your infrastructure is broken?

This trinity works everywhere.

Scale - how will this decision affect me in 5 years?

Fault tolerance - what's my backup plan?

Availability - how do I stay consistent with my goals?

System Design is a must for every Software Engineer