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Difficulty: MediumCost-Optimized Storage Tiering and Lifecycle Management

An online education platform generates user session interaction logs that are stored in an Amazon S3 bucket. Each log file is approximately 200 KB200\text{ KB} in size. The logs are accessed frequently for analysis during the first 1212 days after creation. After 1212 days, access drops significantly, but the logs must be retained for troubleshooting purposes for a total of 2525 days from creation, after which they can be safely deleted. Which lifecycle configuration is the most cost-effective solution for managing these logs?

  1. Keep the logs in Amazon S3 Standard, and configure a lifecycle rule to permanently delete the logs after 25 days.Answer
  2. B
    Configure a lifecycle rule to transition the logs to Amazon S3 Standard-Infrequent Access (S3 Standard-IA) after 12 days and permanently delete them after 25 days.
  3. C
    Configure a lifecycle rule to transition the logs to Amazon S3 One Zone-Infrequent Access (S3 One Zone-IA) after 12 days and permanently delete them after 25 days.
  4. D
    Configure a lifecycle rule to transition the logs to Amazon S3 Glacier Instant Retrieval after 12 days and permanently delete them after 25 days.

Answer

Keep the logs in Amazon S3 Standard and delete them after 25 days using a lifecycle rule.
The correct answer is correct because keeping the logs in Amazon S3 Standard for the entire 25 days is the most cost-effective choice. Transitioning to any Infrequent Access or Glacier tier incurs a minimum storage duration fee (30 days for S3 Standard-IA/S3 One Zone-IA, and 90 days for S3 Glacier Instant Retrieval). Because the logs are deleted at day 25, they only spend 13 days in the target storage tier, which triggers early deletion charges. In addition, transitioning files introduces request costs that outweigh any potential storage savings.

Step-by-Step Solution

1
Calculate the time spent in the secondary storage tier if transitioned at day 12 and deleted at day 25.
The duration in the secondary tier is 25−12=1325 - 12 = 13 days.
This determines whether the storage duration meets the minimum requirements of the target storage classes.
2
Evaluate the minimum storage duration requirements for S3 Standard-IA, S3 One Zone-IA, and S3 Glacier Instant Retrieval.
S3 Standard-IA and S3 One Zone-IA require a minimum of 3030 days, while S3 Glacier Instant Retrieval requires 9090 days.
If objects are deleted before the minimum duration, AWS bills for the remaining days of the minimum duration.
3
Compare the cost of keeping the objects in S3 Standard for 25 days against transitioning them at day 12.
Transitioning triggers an early deletion fee for the remaining days (e.g., 17 days for Standard-IA) plus transition request charges, which exceeds the cost of keeping the logs in S3 Standard for the entire 25 days.
This identifies the most cost-effective lifecycle configuration for the given lifecycle timeline.

Key Concept

S3 lifecycle transition constraints and minimum storage durations
Estimated Time:1m 30s
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Topics

Cost-Optimized Storage Tiering and Lifecycle Management