Disaster Recovery (DR) strategies

By understanding Disaster Recovery (DR) strategies, we can match the Recovery Time Objective (RTO) and Recovery Point Objective (RPO) requirements of the applications to the appropriate DR strategy, while balancing operational costs.

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Here are the listed in order of increasing cost and decreasing recovery time (RTO):

1. Backup and Restore Strategy

Backup application data and configurations to a storage service (e.g., Amazon S1). Rebuild the application from scratch during recovery.

  1. RTO: Longest among DR strategies (hours to days).
  2. RPO: Depends on backup frequency.
  3. Cost: Lowest.
  4. Use Case: Suitable for non-critical applications or when budget constraints exist.

2. Pilot Light Strategy(important)

Maintain a minimal, essential replica of the core application environment in a DR region. Most resources are turned off and activated during failover.

  1. RTO: 10s to minutes
  2. RPO: Minimal, based on data replication frequency.
  3. Cost: Low, as only essential components run actively.
  4. Use Case: Applications requiring faster recovery than Backup and Restore but with cost constraints.

3. Warm Standby Strategy

A scaled-down version of the full production environment runs continuously in the DR region. During a disaster, scale up the resources to handle the full workload.

  1. RTO: lower than Pilot Light.
  2. RPO: Minimal, as data replication is ongoing.
  3. Cost: Medium, as some resources are continuously running. More expensive than Pilot Light.
  4. Use Case: Suitable for critical applications needing faster recovery while balancing costs.

4. Multi-Site (Active-Active) Strategy

Fully duplicate production environments in two or more locations. All environments actively handle traffic and workloads. In case of failure, traffic is redirected seamlessly to the surviving site(s).

  1. RTO: Near-zero.
  2. RPO: Near-zero.
  3. Cost: Highest, as the full environment runs continuously in multiple locations.
  4. Use Case: Mission-critical applications with zero tolerance for downtime.
5. Question

A company is designing a disaster recovery (DR) architecture for an important application on AWS. The company has determined that the recovery time objective (RTO) is 5 minutes with a minimal running instance capacity to support the application in the AWS DR site. The company needs to minimize costs for the DR architecture.

Which DR strategy will meet these requirements?

  1. Warm standby(Correct)
  2. Pilot light
  3. Multi-site active-active
  4. Backup and restore