Why do databases replicate data instead of just running on one powerful machine?
Replication solves three problems a single machine can't: fault tolerance (a copy survives if one machine fails), read scaling (multiple replicas can serve read traffic in parallel), and latency (data placed geographically closer to users reaches them faster). No single machine, however powerful, provides any of these — they require copies of the data existing in more than one place.
Answered in
Database Replication Explained: Single-Leader, Multi-Leader, and LeaderlessWhat replication lag actually breaks, and how single-leader, multi-leader, and leaderless models trade off consistency for availability.
Read the full analysisOther questions this article answers
More system design & architecture questions
- What does CodeDeploy RESTART actually deploy?
- Does CodeDeploy RESTART work with ECS or Lambda?
- Does RESTART remove an application from load-balancer traffic while it restarts?
- Does Elastic Beanstalk's Active Directory join require a domain password?
- Can an Elastic Beanstalk environment be healthy if the domain join fails?
- Will enabling Active Directory replace running instances?
- What is different about AWS Lambda Web Functions?
- Does Lambda Web Functions automatically cost less than ordinary Lambda?
Every answer on Crashtech is written by the editor of the article it comes from — never auto-summarised. Browse all answers or the System Design & Architecture beat.