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One data center or several: the placement choice that trades cost against survival.
Quick Definition
Zonal resources live in a single availability zone, while regional resources span multiple zones for higher resilience. The choice affects availability, latency, and cost, regional redundancy improves fault tolerance but can increase resource and cross-zone data-transfer charges.
Zonal resources live in a single availability zone, one physical data center cluster, while regional resources are spread across several zones in a region automatically. The choice is a direct trade: zonal is cheaper and simpler; regional survives a data center failure without downtime.
The decision should follow workload criticality. Customer-facing production systems usually justify regional placement, since an outage costs more than the redundancy. Development environments, batch jobs, and anything easily recreated can run zonal and bank the savings. Cross-zone data replication and traffic carry real charges, so regional designs cost more in both capacity and data transfer.
Example. A team runs its production database regionally and its nightly analytics cluster zonally. When a zone fails, customers notice nothing, the analytics job restarts in a healthy zone an hour later, and nobody paid for resilience the batch job never needed.
Mistakes run in both directions: critical systems in a single zone are outage debt, while regional redundancy on throwaway workloads is quiet waste. Reviewing placement against actual criticality is one of the cleaner architecture-level savings. The availability zone guide covers the mechanics, and the scalability guide frames the resilience trade-offs.
Regional typically costs more through duplicated capacity and cross-zone replication traffic. The premium varies by service, often 50 to 100 percent.
Anything whose downtime costs more than redundancy: customer-facing services, payment paths, and data stores that cannot lose writes.
Yes, regions protect against zone failure; multi-region protects against regional disasters, at much higher cost. Few workloads truly need it.