Global infrastructure: region vs availability zone vs region pair vs sovereign region
Verdict: A geographical area of nearby datacentres, a region. Physically separate datacentres inside a region, availability zones. Two linked regions 300+ miles apart for disaster recovery, a region pair. Isolated for compliance, a sovereign region.
| Criterion | Azure region | Availability zone | Region pair | Sovereign region |
|---|---|---|---|---|
| Scope | Geographical area of datacentres | Inside one region | Two regions in a geography | Isolated Azure instance |
| Protects against | Groups nearby low-latency datacentres | Single datacentre or zone failure | Regional disaster | Compliance and legal exposure |
| Choose when | Pick where to deploy | Survive a zone fault in-region | Cross-region failover 300 miles apart | Azure Government-style isolation |
Rules
- A region is a geographical area containing one or more datacentres near one another on a low-latency network.
- An availability zone is one or more physically separate datacentres within a region, each with independent power, cooling and networking, acting as an isolation boundary.
- A region pair links two regions in the same geography at least 300 miles apart, so replication lets services fail over if one region has a disaster.
- A sovereign region is an instance of Azure isolated from the main instance for legal or compliance reasons, such as Azure Government.
Traps
- Availability zones protect within one region; cross-region, 300-mile failover needs a region pair.
- A sovereign region is a compliance-isolated instance, not a disaster-recovery link between two regions.