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Difficulty: EasyMulti-AZ, Multi-Region Architectures and Disaster Recovery (DR)

A media company is planning a disaster recovery (DR) strategy on AWS. The solutions architect recommends implementing a Pilot Light strategy in a secondary AWS Region to achieve a low Recovery Time Objective (RTO) while keeping idle resource costs to a minimum.

Which of the following actions should the solutions architect take to implement this strategy? (Select TWO.)

  1. Replicate the primary database to a continuously running database instance in the secondary AWS Region to keep the data up to date.Answer
  2. Maintain application server configurations as Amazon Machine Images (AMIs) and launch the instances only during a failover event.Answer
  3. C
    Keep a scaled-down fleet of application EC2 instances running behind an Elastic Load Balancer in the secondary AWS Region.
  4. D
    Store all database backups in Amazon S3 Glacier Flexible Retrieval and restore them to new database instances during a failover.
  5. E
    Configure an Amazon RDS cross-region read replica and use it as the primary automated Multi-AZ failover target for write operations.

Answer

Replicate the primary database to a continuously running database instance in the secondary AWS Region, and maintain application server configurations as Amazon Machine Images (AMIs) to launch only during failover.
In a Pilot Light disaster recovery (DR) strategy, the data tier (such as the database) is kept running and continuously updated in the recovery region to minimize recovery time. Compute and application infrastructure are kept dormant or stored as configuration templates (like AMIs) to minimize idle running costs. These templates are only used to provision active instances when a failover is triggered.

Step-by-Step Solution

1
Identify the key constraints of a Pilot Light disaster recovery strategy.
Pilot Light requires databases (the 'pilot light') to be running and replicating data, while application servers and other compute infrastructure are kept turned off or defined as templates to minimize costs.
This establishes the baseline architectural pattern for Pilot Light, separating the data layer (always running/replicating) from the compute layer (decommissioned/dormant).
2
Evaluate the database tier configuration.
The database must be replicated to the recovery region in real-time or near real-time, requiring a running database instance to host and apply the replicated data.
This guarantees that the data is current and ready for use without lengthy restore operations from backups, keeping RTO low.
3
Evaluate the compute tier configuration.
Application servers should not be running. Instead, they should be prepared as AMIs or CloudFormation templates, ready to be provisioned only when a disaster is declared.
This satisfies the requirement to minimize idle compute cost, distinguishing Pilot Light from Warm Standby (where scaled-down servers are running).

Key Concept

Pilot Light Disaster Recovery Strategy
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Topics

Multi-AZ, Multi-Region Architectures and Disaster Recovery (DR)

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