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

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