multi-region-deployment

# Multi-Region Deployment

Comprehensive guide to deploying applications across multiple geographic regions for availability, performance, and disaster recovery.

## When to Use This Skill

- Designing globally distributed applications
- Implementing disaster recovery (DR)
- Reducing latency for global users
- Meeting data residency requirements
- Achieving high availability (99.99%+)
- Planning failover strategies

## Multi-Region Fundamentals

### Why Multi-Region?

```text
Reasons for Multi-Region:

1. High Availability
   └── Survive region-wide failures
   └── Natural disasters, power outages
   └── Target: 99.99%+ uptime

2. Low Latency
   └── Serve users from nearest region
   └── Reduce round-trip time
   └── Better user experience

3. Data Residency
   └── GDPR, data sovereignty laws
   └── Keep data in specific countries
   └── Compliance requirements

4. Disaster Recovery
   └── Business continuity
   └── RTO/RPO requirements
   └── Regulatory requirements

Trade-offs:
+ Higher availability
+ Lower latency globally
+ Compliance capability
- Higher cost (2x-3x or more)
- Increased complexity
- Data consistency challenges
```

### Deployment Models

```text
Model 1: Active-Passive (DR)
┌─────────────────┐         ┌─────────────────┐
│  PRIMARY (Active)│         │ SECONDARY (Passive)│
│  ┌─────────────┐│         │  ┌─────────────┐│
│  │     App     ││   ──►   │  │    App      ││
│  │    (Live)   ││  Sync   │  │  (Standby)  ││
│  └─────────────┘│         │  └─────────────┘│
│  ┌─────────────┐│         │  ┌─────────────┐│
│  │     DB      ││   ──►   │  │    DB       ││
│  │  (Primary)  ││  Replic │  │  (Replica)  ││
│  └─────────────┘│         │  └─────────────┘│
└─────────────────┘         └─────────────────┘
    All traffic              Failover only

Model 2: Active-Active (Load Distributed)
┌─────────────────┐         ┌─────────────────┐
│   REGION A       │         │   REGION B       │
│  ┌─────────────┐│    ◄──► │  ┌─────────────┐│
│  │     App     ││  U