Disaster Recovery (DR) scenarios in AWS are critical strategies for ensuring business continuity when unexpected failures occur. AWS offers four primary DR approaches, each balancing cost against recovery time objectives (RTO) and recovery point objectives (RPO).
**Backup and Restore** is the most…Disaster Recovery (DR) scenarios in AWS are critical strategies for ensuring business continuity when unexpected failures occur. AWS offers four primary DR approaches, each balancing cost against recovery time objectives (RTO) and recovery point objectives (RPO).
**Backup and Restore** is the most cost-effective approach with the longest recovery time. Data is regularly backed up to S3, and infrastructure is recreated from scratch during a disaster. This suits non-critical workloads where extended downtime is acceptable.
**Pilot Light** maintains minimal core infrastructure components running continuously in the DR region. Critical databases remain synchronized, but application servers stay dormant until needed. During failover, you scale up the environment and redirect traffic. This provides faster recovery than backup-restore while controlling costs.
**Warm Standby** keeps a scaled-down but fully functional version of your production environment running in another region. All components operate continuously at reduced capacity. When disaster strikes, you scale resources to handle production loads. This approach offers quicker RTO than pilot light.
**Multi-Site Active-Active** runs full production environments across multiple regions simultaneously, handling traffic in parallel. This provides near-zero RTO and RPO but represents the highest cost option. Route 53 health checks and DNS failover enable automatic traffic redirection.
**Key AWS Services for DR:**
- Amazon S3 with Cross-Region Replication for data durability
- AWS Backup for centralized backup management
- RDS Multi-AZ and Read Replicas for database resilience
- CloudFormation for infrastructure automation
- Route 53 for DNS-based failover
- AWS Global Accelerator for traffic management
When designing DR solutions, consider regulatory requirements, acceptable downtime, data loss tolerance, and budget constraints. Testing DR procedures regularly through planned failover exercises ensures your recovery processes work when needed most.
Disaster Recovery Scenarios - AWS Solutions Architect Professional
Why Disaster Recovery is Important
Disaster recovery (DR) is critical for business continuity. Organizations must ensure their applications and data remain available even when catastrophic events occur, such as natural disasters, hardware failures, cyberattacks, or human errors. AWS provides multiple strategies to help organizations recover from disasters with varying levels of cost, complexity, and recovery time.
What is Disaster Recovery?
Disaster recovery refers to the policies, tools, and procedures designed to enable the recovery or continuation of vital technology infrastructure and systems following a natural or human-induced disaster. Two key metrics define DR requirements:
Recovery Time Objective (RTO) - The maximum acceptable time that an application can be offline after a disaster occurs.
Recovery Point Objective (RPO) - The maximum acceptable amount of data loss measured in time. This determines how frequently you need to back up your data.
The Four DR Strategies
1. Backup and Restore (Lowest Cost, Highest RTO/RPO) - Data is backed up to S3, Glacier, or other storage - Infrastructure is recreated from scratch during recovery - RTO: Hours to days - RPO: Hours (depends on backup frequency) - Best for: Non-critical workloads where extended downtime is acceptable
2. Pilot Light - Core infrastructure components are kept running in a minimal state - Critical data is continuously replicated - During disaster, resources are scaled up and additional components are started - RTO: Minutes to hours - RPO: Minutes - Best for: Workloads requiring faster recovery than backup/restore
3. Warm Standby - A scaled-down but fully functional version of your environment runs continuously - All services are running but at minimal capacity - During disaster, resources are scaled up to handle production load - RTO: Minutes - RPO: Seconds to minutes - Best for: Business-critical applications requiring quick recovery
4. Multi-Site Active/Active (Highest Cost, Lowest RTO/RPO) - Full production environment runs in multiple regions simultaneously - Traffic is distributed across all sites using Route 53 - Near-zero downtime during failover - RTO: Near zero - RPO: Near zero - Best for: Mission-critical applications requiring maximum availability
Key AWS Services for DR
- Amazon S3: Cross-region replication for data backup - AWS Backup: Centralized backup management across AWS services - Amazon RDS: Multi-AZ deployments and cross-region read replicas - Amazon Aurora Global Database: Sub-second cross-region replication - AWS Elastic Disaster Recovery (DRS): Continuous replication for rapid recovery - Route 53: DNS failover and health checks - CloudFormation/Terraform: Infrastructure as code for rapid deployment - AWS Global Accelerator: Automatic failover between regions
How to Answer DR Questions in the Exam
Step 1: Identify the RTO and RPO requirements Look for phrases like "must recover within minutes" (low RTO) or "cannot afford to lose more than one hour of data" (RPO of one hour).
Step 2: Match requirements to the appropriate strategy - Hours of acceptable downtime = Backup and Restore - Minutes of acceptable downtime = Pilot Light or Warm Standby - Near-zero downtime required = Multi-Site Active/Active
Step 3: Consider cost constraints If the question mentions budget limitations, lean toward less expensive options like Backup and Restore or Pilot Light.
Step 4: Evaluate the specific services mentioned Questions may specify certain services. Know which DR features each service supports.
Exam Tips: Answering Questions on Disaster Recovery Scenarios
1. Always calculate the trade-off between cost and recovery time. Lower RTO/RPO means higher costs. Choose the most cost-effective solution that meets the stated requirements.
2. Pay attention to whether the scenario mentions "data" or "application" recovery. Data recovery focuses on backups and replication, while application recovery includes compute resources.
3. Know the difference between Pilot Light and Warm Standby. Pilot Light keeps only core components running (like databases), while Warm Standby runs all components at reduced capacity.
4. Route 53 failover routing is commonly tested. Understand how health checks trigger automatic DNS failover to secondary regions.
5. Multi-AZ is for high availability, not disaster recovery. Multi-AZ protects against AZ failures within a region. Cross-region solutions are needed for regional disasters.
6. Look for keywords in questions: - "Cost-effective" typically points to Backup and Restore or Pilot Light - "Minimal data loss" suggests solutions with continuous replication - "Business continuity" often requires Warm Standby or Multi-Site
7. Understand AWS Elastic Disaster Recovery (DRS). This service enables sub-second RPOs through continuous replication and is increasingly featured in exam questions.
8. Remember that Global Accelerator and Route 53 serve different purposes. Global Accelerator provides static IP addresses with instant failover, while Route 53 provides DNS-based routing with TTL considerations.
9. For database DR, know your options: RDS Multi-AZ (HA within region), Read Replicas (can be promoted), Aurora Global Database (fastest cross-region), DynamoDB Global Tables (multi-region active-active).
10. Infrastructure as Code accelerates recovery. CloudFormation templates stored in version control enable rapid infrastructure recreation during disasters.