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region and zone
A zone is a data center. A region is a group of them. Two instances in one zone are one fire.
What is region and zone?
Availability zones fail independently inside a region: power, network. Regions fail more rarely and cost latency and data transfer between them. “Multi-AZ” is not “multi-region.” Cross-region writes pay lag and money.
Why does region and zone matter when vibe coding?
Models say “deploy globally” and create two containers in the default zone. Name the failure you are buying off.
How do you do region and zone?
Start multi-AZ for the database and the app if an zone outage is unacceptable. Multi-region only when you have a written story for data residency and conflict. Test by killing a zone, not by hoping.
How do you ask a model for region and zone?
Run (service) in more than one availability zone in (region). Do not claim multi-region. Document what a zone loss does. Do not replicate writes across regions unless the conflict rule is specified.
What goes wrong with region and zone?
A load balancer in one zone in front of “multi-AZ” servers. The balancer is the single point. It has to be redundant too.