Millions of users and beyond

Scaling a system is an iterative process. Iterating on what we have learned in this chapter could get us far. More fine-tuning and new strategies are needed to scale beyond millions of users. For example, you might need to optimize your system and decouple the system into even smaller services. All the techniques learned in this chapter should provide a good foundation to tackle new challenges. To conclude this chapter, we provide a summary of how we scale our system to support millions of users:

• Keep web tier stateless

• Build redundancy at every tier

• Cache data as much as you can

• Support multiple data centers

• Host static assets in CDN

• Scale your data tier by sharding

• Split tiers into individual services

• Monitor your system and use automation tools