2.1.1. Regions and Availability Zones

💡 First Principle: AWS Regions are distinct geographic areas with multiple isolated Availability Zones (AZs). This fundamental design provides high availability, fault tolerance, and disaster recovery.

An AWS Region is a physical location in the world where AWS clusters data centers. Each Region is completely independent and isolated from other Regions.

Key Concepts:

• Regions:
  • Purpose: Provide geographic isolation for disaster recovery. If one Region is affected by a disaster, applications can failover to another Region.
  • Selection Factors: Compliance (data residency), proximity to users (latency), and service availability (not all services are in all Regions).
• Availability Zones (AZs):
  • Purpose: Isolated data centers within a Region, providing high availability and fault tolerance.
  • Isolation: AZs are physically separate, minimizing impact of localized failures (e.g., power outage, fire, flood in one data center).
  • Low-Latency Connectivity: AZs within a Region are connected by low-latency, high-throughput, and redundant networking. This allows applications to span multiple AZs for continuous operation.

Scenario: A company needs to deploy an application that must remain operational even if one data center experiences an outage. They choose to deploy components across at least two Availability Zones (AZs) within the same AWS Region.

Reflection Question: How does distributing resources across AZs (e.g., deploying servers in multiple AZs) fundamentally enhance application resilience against localized failures (like a power outage in one data center) and ensure high availability?