A logistics company is optimizing the deployment costs of its application portfolio on AWS… — AWS Certified Solutions Architect - Associate

A logistics company is optimizing the deployment costs of its application portfolio on AWS. The portfolio consists of the following workloads:
- A legacy enterprise resource planning (ERP) system hosted on Amazon EC2 instances that must run $24/7$ and cannot tolerate any service interruptions.
- A batch image-transcoding application hosted on AWS Fargate that processes files uploaded throughout the day, where tasks can be interrupted and retried without affecting the final output.
- A set of AWS Lambda functions that execute periodically to process API event requests.
- An Amazon RDS for PostgreSQL database instance that stores transactional data and must remain online continuously.

Which strategy should a solutions architect recommend to achieve the most cost-effective solution?

Purchase a Compute Savings Plan to cover the Amazon EC2 instances and AWS Lambda functions. Configure the AWS Fargate tasks for the image-transcoding application to use the Fargate Spot capacity provider. Purchase an Amazon RDS Reserved Instance for the PostgreSQL database.Answer
B
Purchase a single Compute Savings Plan to cover the Amazon EC2 instances, AWS Lambda functions, and the Amazon RDS for PostgreSQL database. Configure the AWS Fargate tasks for the image-transcoding application to use the Fargate Spot capacity provider.
C
Purchase an EC2 Instance Savings Plan to cover the Amazon EC2 instances and the Amazon RDS for PostgreSQL database. Purchase a Compute Savings Plan to cover the AWS Lambda functions and the AWS Fargate tasks for the image-transcoding application.
D
Migrate the PostgreSQL database from Amazon RDS to run continuously as a containerized database within AWS Lambda functions configured with provisioned concurrency. Purchase a Compute Savings Plan to cover the Amazon EC2 instances, Fargate tasks, and Lambda functions.

Answer

Purchase a Compute Savings Plan to cover the Amazon EC2 instances and AWS Lambda functions. Configure the AWS Fargate tasks for the image-transcoding application to use the Fargate Spot capacity provider. Purchase an Amazon RDS Reserved Instance for the PostgreSQL database.

The correct strategy combines a Compute Savings Plan to cover the Amazon EC2 instances and AWS Lambda functions, uses Fargate Spot for the fault-tolerant image-transcoding tasks, and utilizes an Amazon RDS Reserved Instance for the PostgreSQL database. Compute Savings Plans automatically apply across EC2, Fargate, and Lambda. Because the Fargate workload is batch-oriented and tolerant of interruptions, Fargate Spot offers the lowest cost model. Amazon RDS is not covered by Compute Savings Plans, so a dedicated RDS Reserved Instance must be purchased for the database instance.

Step-by-Step Solution

Analyze the workload characteristics and flexibility.

Identify that the legacy ERP system on EC2 and the RDS database require continuous

24/7

availability. The image-transcoding application on Fargate is fault-tolerant and can handle interruptions. The Lambda functions run periodically.

Matching workload needs to the appropriate purchasing models ensures high availability where required and maximum discounts where flexibility exists.

Determine the purchasing model for the Fargate batch application.

Select the Fargate Spot capacity provider.

Since the image-transcoding tasks can tolerate interruptions, Fargate Spot provides up to a

70\%

discount compared to Fargate On-Demand without needing commit-based savings plans.

Determine the coverage scope of Compute Savings Plans.

Map the Compute Savings Plan to the Amazon EC2 instances and AWS Lambda functions.

Compute Savings Plans apply to EC2, Fargate, and Lambda. Since the Fargate component is already optimized via Fargate Spot, the Compute Savings Plan will cover the baseline ERP EC2 instances and the event-driven Lambda functions.

Address the Amazon RDS database instance cost optimization.

Select an Amazon RDS Reserved Instance.

Compute Savings Plans do not cover RDS instances. An RDS Reserved Instance is the correct vehicle to obtain discounts for steady-state RDS database instances.

Key Concept

Compute Savings Plans apply to EC2, Fargate, and Lambda, but not RDS; RDS requires Reserved Instances.

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Step-by-Step Solution

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