Azure Multi-Region Architecture
Compute: VM Scale Sets and AKS
Deploy VM Scale Sets or AKS clusters in paired Azure regions (e.g., West Europe + North Europe). Azure Paired Regions receive coordinated maintenance and sequential updates to prevent simultaneous outages. Use ARM templates with parameter files per region for consistent deployment.
Database: Cosmos DB multi-region
Azure Cosmos DB provides turnkey multi-region replication with automatic or manual failover. Multi-region writes enable active-active database patterns where both regions accept writes simultaneously. For SQL workloads, Azure SQL with active geo-replication provides cross-region read replicas with automatic failover groups.
Routing: Azure Traffic Manager
Traffic Manager provides DNS-based load balancing with health probes. Priority routing sends all traffic to the primary region until it fails. Performance routing sends users to the nearest healthy region. Geographic routing can direct users to specific regions based on location.
Cross-Region Data Consistency Challenges
- Replication lag: Asynchronous replication means the secondary region may be seconds behind. Design applications to handle eventual consistency or use synchronous replication for critical data (at the cost of latency).
- Conflict resolution: Active-active write patterns require conflict resolution strategies — last-writer-wins, application-level merge, or domain-specific rules.
- Data residency: Cross-region replication may conflict with data residency requirements (GDPR). Ensure replication targets comply with applicable regulations.
How Opsio Designs Multi-Region DR
- Architecture assessment: We evaluate your RTO/RPO requirements and recommend the right multi-region pattern.
- Implementation: We deploy multi-region infrastructure with automated failover using IaC (Terraform/CloudFormation).
- Database replication: We configure Aurora Global Database, Cosmos DB, or Azure SQL geo-replication based on your platform.
- Failover testing: Quarterly automated failover drills to validate recovery works as designed.
- Cost optimization: We right-size standby infrastructure to minimize DR costs while meeting RTO requirements.
Frequently Asked Questions
How much does multi-region DR cost?
Pilot light adds 10-20% to your infrastructure cost. Warm standby adds 30-50%. Active-active roughly doubles your compute cost but can be optimized through intelligent traffic routing. The right architecture balances cost against your business's tolerance for downtime.
Which AWS regions should I use for DR?
Choose regions that are geographically separate but close enough for acceptable latency. For EU: Stockholm (eu-north-1) primary with Frankfurt (eu-central-1) or Ireland (eu-west-1) as DR. For India: Mumbai (ap-south-1) primary with Hyderabad (ap-south-2) as DR.
Can I do multi-region with Kubernetes?
Yes. Deploy EKS or AKS clusters in multiple regions with identical configurations through GitOps (ArgoCD, Flux). Use external-dns and Route 53/Traffic Manager for cross-region service discovery. StatefulSets require careful handling — use managed databases with cross-region replication rather than in-cluster databases for DR.