AWS Disaster Recovery Architectures

Overview

AWS provides four main disaster recovery architectures, each offering different trade-offs between recovery speed and cost. These architectures range from simple backup solutions to fully active multi-site deployments.

1. Backup and Restore

Description

The most basic DR strategy, focusing on data backup to AWS.

Characteristics

• Minimal configuration required

• Low risk implementation

• Most cost-effective option

• Longest recovery time

Implementation Examples

• AWS Snowball for data transfer

• Virtual Tape Library

• AWS Storage Gateway

• S3 for backup storage

Limitations

• Limited flexibility

• Functions primarily as offsite backup

• Longest recovery time of all options

• Manual recovery process required

2. Pilot Light

Description

Maintains minimal AWS footprint in standby mode, similar to a pilot light on a gas heater.

Characteristics

• Cost-effective hot site alternative

• Core services maintained in ready state

• Requires some manual intervention

• Minutes to hours for full recovery

Implementation Components

• Small RDS instance for database replication

• Stopped EC2 instances for web/app servers

• Regular AMI updates required

• Basic infrastructure maintained

Recovery Process

1. Start stopped EC2 instances

2. Scale up RDS instance if needed

3. Redirect traffic to AWS environment

4. Validate application functionality

Considerations

• AMI maintenance crucial

• Regular testing required

• Database synchronization needed

• Cost-effective middle ground

3. Warm Standby

Description

Maintains a scaled-down but fully functional environment in AWS.

Characteristics

• More responsive than pilot light

• Services already running

• Can serve as staging environment

• Reduced recovery time

Implementation Components

• Active load balancer configuration

• Running web and application servers

• Replicated database infrastructure

• Route 53 for traffic management

Recovery Process

1. Scale up existing resources

• Increase EC2 instance sizes

• Add more instances as needed

• Upgrade database capacity

1. Update DNS routing

• Redirect traffic through Route 53

• Scale resources to match demand

Advantages

• Faster recovery than pilot light

• Environment already validated

• Can serve dual purpose (staging)

• Automated scaling possible

4. Multi-Site Active/Active

Description

Full production environment maintained in AWS, running alongside primary site.

Characteristics

• Fastest recovery time

• Minimal to no manual intervention

• Seconds or less to failover

• Most expensive option

Implementation Components

• Fully active load balancers

• Production-scaled EC2 instances

• Active database replication

• Route 53 health checks

Recovery Process

1. Automatic failover via Route 53

2. DNS propagation (based on TTL)

3. Traffic automatically redirected

4. No manual intervention required

Considerations

• Highest cost option

• Perceived resource waste

• DNS TTL impact on recovery

• Complex synchronization requirements

Cost vs Recovery Time Trade-offs

Cost Spectrum (Low to High)

1. Backup and Restore

2. Pilot Light

3. Warm Standby

4. Multi-Site

Recovery Time Spectrum (Slow to Fast)

1. Backup and Restore (Hours/Days)

2. Pilot Light (Hours)

3. Warm Standby (Minutes)

4. Multi-Site (Seconds)

Best Practices

Architecture Selection

• Align with business RTO/RPO

• Consider budget constraints

• Account for technical capabilities

• Plan for growth

Implementation

• Regular testing required

• Document procedures

• Automate where possible

• Monitor and maintain synchronization

Maintenance

• Keep AMIs current

• Test failover procedures

• Update documentation

• Train staff on procedures