Pilot light disaster recovery is a cost-effective AWS strategy that maintains a minimal version of your production environment in a secondary region, ready to scale up when disaster strikes. The term comes from the small flame in gas heaters that can quickly ignite the full system when needed.
In …Pilot light disaster recovery is a cost-effective AWS strategy that maintains a minimal version of your production environment in a secondary region, ready to scale up when disaster strikes. The term comes from the small flame in gas heaters that can quickly ignite the full system when needed.
In this approach, you keep only the most critical core elements of your infrastructure running at all times in the recovery region. Typically, this includes database servers with continuous replication from your primary site. Other components like application servers and web servers remain pre-configured but turned off, stored as AMIs (Amazon Machine Images) ready for rapid deployment.
Key components of a pilot light setup include:
1. **Data Replication**: Continuous synchronization of databases using services like RDS cross-region read replicas, Aurora Global Database, or S3 cross-region replication ensures your data remains current in the recovery region.
2. **Pre-configured Resources**: AMIs, Launch Templates, and CloudFormation templates are maintained and updated regularly, allowing quick provisioning of compute resources during failover.
3. **Network Configuration**: VPCs, subnets, security groups, and Route 53 DNS configurations are pre-established in the recovery region.
4. **Recovery Process**: When disaster occurs, you scale up the pilot light environment by launching EC2 instances from prepared AMIs, promoting read replicas to primary databases, and updating DNS records to redirect traffic.
Pilot light offers a balance between cost and recovery time, with typical RTO (Recovery Time Objective) of minutes to hours and RPO (Recovery Point Objective) of seconds to minutes depending on replication lag. It costs less than warm standby or multi-site active-active configurations since most compute resources remain offline during normal operations.
This strategy suits organizations requiring faster recovery than backup-and-restore methods but where the additional expense of maintaining fully running standby infrastructure cannot be justified.
Pilot Light Disaster Recovery - Complete Guide
What is Pilot Light Disaster Recovery?
Pilot Light is a disaster recovery (DR) strategy where a minimal version of your environment is always running in a secondary AWS region. The term comes from the pilot light on a gas furnace - a small flame that is always on and can quickly ignite the full furnace when needed.
In this approach, only the most critical core elements of your system are kept running, typically including: - Database servers with continuous replication - Core application configurations - Essential AMIs and launch templates
Why is Pilot Light Important?
Pilot Light occupies a strategic middle ground in the DR spectrum:
Cost Efficiency: It costs less than maintaining a fully scaled environment (Warm Standby or Multi-Site) while providing faster recovery than Backup and Restore.
Reduced RTO: Recovery Time Objective is typically measured in minutes to hours rather than hours to days, since core components are already running.
Data Protection: Continuous database replication means minimal data loss (low RPO - Recovery Point Objective).
Business Continuity: Organizations can meet compliance requirements and SLAs for critical workloads.
How Pilot Light Works
Normal Operations: 1. Primary region handles all production traffic 2. Database replication occurs continuously to the DR region (using services like RDS Read Replicas, Aurora Global Database, or database-native replication) 3. AMIs and configurations are kept synchronized 4. Minimal compute resources run in DR region (or none at all for true pilot light)
During Failover: 1. Detect the disaster or trigger manual failover 2. Promote the replicated database to become the primary 3. Scale up compute resources (launch EC2 instances, scale Auto Scaling groups) 4. Update DNS records (Route 53) to point to the DR region 5. Verify application functionality
Key AWS Services for Pilot Light
- Amazon RDS: Cross-region read replicas for database replication - Amazon Aurora Global Database: Sub-second replication across regions - Amazon S3: Cross-region replication for static assets - AWS CloudFormation/Terraform: Infrastructure as Code for rapid provisioning - Amazon Route 53: DNS failover and health checks - AWS Auto Scaling: Rapid scaling of compute resources - AWS Systems Manager: Automation for failover procedures
Pilot Light vs Other DR Strategies
Backup and Restore: Lower cost but higher RTO (hours to days). No running resources in DR region.
Pilot Light: Core systems running, moderate cost, RTO in minutes to hours.
Multi-Site Active-Active: Full production capacity in multiple regions. Highest cost, near-zero RTO.
Exam Tips: Answering Questions on Pilot Light Disaster Recovery
Identify Pilot Light Scenarios: - Questions mentioning 'minimal running resources' with 'database replication' - Requirements for RTO of 10 minutes to a few hours - Cost-conscious organizations needing faster recovery than backup/restore - Scenarios requiring 'core elements' to be maintained
Key Differentiators to Remember: - Pilot Light = databases replicated + minimal/no compute running - Warm Standby = scaled-down but complete environment running - If the question mentions 'always running at reduced capacity' it is likely Warm Standby, not Pilot Light
Common Exam Patterns: - Watch for RTO/RPO requirements - Pilot Light offers low RPO due to replication but moderate RTO due to scaling time - Cost optimization questions where Backup/Restore is too slow - Questions about promoting read replicas during failover
Red Flags in Answer Choices: - If an answer suggests no database replication, it is Backup and Restore - If an answer mentions full capacity running in both regions, it is Multi-Site - If compute resources are described as 'scaled down but operational,' consider Warm Standby
Remember the Analogy: Like a pilot light on a furnace - always burning minimally, ready to ignite the full system when needed. The 'flame' is your replicated database; the 'furnace' is your full application stack.