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Answer: Use provisioned mode and DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA). Reserve capacity for the forecasted workload.
## Explanation **Correct Answer: A** **Why Option A is correct:** 1. **Constant and predictable workload**: The scenario explicitly states that "the data workload is constant and predictable." This is the ideal scenario for using provisioned capacity mode with reserved capacity. 2. **Cost-effectiveness**: Provisioned capacity with reserved capacity offers the lowest cost for predictable workloads. By reserving capacity for 1 or 3 years, you get significant discounts (up to 70% compared to on-demand pricing). 3. **DynamoDB Standard-IA**: DynamoDB Standard-Infrequent Access (Standard-IA) is a storage class for tables that store infrequently accessed data. While the question doesn't explicitly state the access pattern, if the data analysis happens infrequently, this could provide additional cost savings. 4. **Budget forecasting**: Reserved capacity allows for precise budget forecasting since you pay a fixed amount for the reserved capacity. **Why other options are incorrect:** **Option B**: While provisioned mode is correct for predictable workloads, this option doesn't mention reserving capacity. Without reserved capacity, you're paying the standard provisioned rates, which are higher than reserved capacity rates. **Option C**: On-demand mode is designed for unpredictable workloads with spiky traffic patterns. It's more expensive than provisioned mode for constant, predictable workloads. Setting RCUs/WCUs high enough for changes contradicts the "constant and predictable" nature of the workload. **Option D**: On-demand mode doesn't support specifying RCUs/WCUs with reserved capacity. Reserved capacity is only available for provisioned capacity mode. This option mixes incompatible concepts. **Key AWS Concepts:** - **Provisioned Capacity**: You specify the number of reads and writes per second you expect your application to perform. Best for predictable workloads. - **On-Demand Capacity**: DynamoDB instantly scales up and down to accommodate your workload. Best for unpredictable workloads. - **Reserved Capacity**: Commit to a certain amount of read and write capacity for 1 or 3 years in exchange for significant cost savings. - **DynamoDB Standard-IA**: Lower-cost storage tier for infrequently accessed data, with slightly higher read/write costs but lower storage costs. **Best Practice**: For constant, predictable workloads with budget constraints, always use provisioned capacity with reserved capacity commitments to maximize cost savings.
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A company collects data from a large number of participants who use wearable devices. The company stores the data in an Amazon DynamoDB table and uses applications to analyze the data. The data workload is constant and predictable. The company wants to stay at or below its forecasted budget for DynamoDB.
Which solution will meet these requirements MOST cost-effectively?
A
Use provisioned mode and DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA). Reserve capacity for the forecasted workload.
B
Use provisioned mode. Specify the read capacity units (RCUs) and write capacity units (WCUs).
C
Use on-demand mode. Set the read capacity units (RCUs) and write capacity units (WCUs) high enough to accommodate changes in the workload.
D
Use on-demand mode. Specify the read capacity units (RCUs) and write capacity units (WCUs) with reserved capacity.