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Difficulty: MediumHigh Availability and Disaster Recovery Design

A smart grid utility provider is designing a new telemetry processing system in AWS to ingest meter readings from millions of smart meters. The application's database must be highly available and resilient. The system is designed with a primary Region of `eu-central-1` and a disaster recovery Region of `eu-west-1`. The business requires a Recovery Time Objective (RTO) of 1515 minutes and a Recovery Point Objective (RPO) of 55 minutes. Additionally, outbound communication to external grid APIs must remain highly available within the primary Region, even during a single Availability Zone outage. Which two options should the solutions architect select to meet these requirements?

  1. Deploy an Amazon Aurora Global Database with the primary cluster in eu-central-1 and a secondary cluster in eu-west-1. Configure Aurora replicas across multiple Availability Zones in the primary Region.Answer
  2. B
    Configure subnet route tables in all Availability Zones of the primary Region to route outbound traffic through a single NAT Gateway deployed in a single Availability Zone to minimize NAT Gateway charges.
  3. C
    Set up daily Amazon Aurora database snapshot exports to Amazon S3, copy the snapshots to eu-west-1 using AWS Backup, and restore the database from the copied snapshot during a failover event.
  4. D
    Create a Route 53 Private Hosted Zone for the database in eu-central-1, associate it only with the primary VPC, and use cross-region VPC peering to resolve the database DNS endpoint in eu-west-1.
  5. Deploy NAT Gateways in multiple Availability Zones in the primary VPC, and configure the subnet route table in each Availability Zone to direct outbound traffic through the local NAT Gateway in that same zone.Answer
  6. F
    Deploy a single-node Amazon RDS PostgreSQL instance in the primary Region, and configure Aurora Auto Scaling to dynamically provision a standby instance in the secondary Region to scale out read capacity during traffic spikes.

Answer

Deploying Amazon Aurora Global Database to achieve cross-region replication for RTO/RPO objectives, alongside deploying multiple NAT Gateways in each Availability Zone of the primary Region to ensure high availability for outbound traffic.
Deploying an Amazon Aurora Global Database provides cross-region replication with a typical RPO of less than 1 second and a quick failover RTO, which easily satisfies the 15-minute RTO and 5-minute RPO. Multi-AZ deployment within the primary Region ensures local database high availability. Furthermore, deploying NAT Gateways in multiple Availability Zones in the primary VPC ensures that outbound connectivity to external grid APIs is highly available locally within the Region, removing any single point of failure from an AZ outage.

Step-by-Step Solution

1
Analyze the database RTO and RPO requirements.
RTO is 1515 minutes and RPO is 55 minutes.
Standard cross-region database snapshot copy solutions fail to meet a 55-minute RPO. Amazon Aurora Global Database provides sub-second replication latency, meeting the 55-minute RPO, and can be promoted in minutes, satisfying the 1515-minute RTO.
2
Identify the high availability requirements for outbound network traffic within the primary Region.
NAT Gateways must be deployed in multiple Availability Zones.
A single NAT Gateway in a single AZ represents a single point of failure. If that AZ goes down, outbound connectivity to the grid APIs fails. Placing NAT Gateways in multiple AZs removes this single point of failure.

Key Concept

Designing multi-region disaster recovery and high availability for databases and networking on AWS.
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Topics

High Availability and Disaster Recovery Design

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