Quick Answer
The answer is Amazon S3 Standard-Infrequent Access (S3 Standard-IA). This storage class is the most cost-effective solution for storing semi-structured JSON logs for up to 30 days with infrequent access because it balances lower storage costs than S3 Standard with the same low-latency retrieval and 99.999999999% durability across multiple Availability Zones, making it ideal for data that is rarely accessed but must be available immediately when needed. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your ability to match storage classes to access patterns, often appearing as a trap where candidates mistakenly choose S3 Glacier for infrequent logs, forgetting that Glacier imposes retrieval delays and minimum storage durations that exceed 30 days. Remember the memory tip: “IA for logs you rarely touch, but need in a clutch.”
This DEA-C01 practice question tests your understanding of data store management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A data engineer needs to store semi-structured JSON logs from an application for up to 30 days, with infrequent access. Which storage solution is the most cost-effective?
Amazon S3 Glacier Deep Archive
Why wrong: Designed for long-term archival, not suitable for 30-day access.
Amazon S3 One Zone-Infrequent Access (S3 One Zone-IA)
Why wrong: Less durable; logs may need cross-AZ resilience.
Amazon S3 Standard
Why wrong: More expensive for infrequent access patterns.
Amazon S3 Standard-Infrequent Access (S3 Standard-IA)
Cost-effective for infrequently accessed data with rapid access needs.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Amazon S3 Standard-Infrequent Access (S3 Standard-IA)
Amazon S3 Standard-Infrequent Access (S3 Standard-IA) is the most cost-effective choice for storing semi-structured JSON logs for up to 30 days with infrequent access. It offers low storage cost (compared to S3 Standard) while providing low-latency retrieval and high durability (99.999999999%) across multiple Availability Zones, making it ideal for data that is accessed less frequently but needs immediate availability when requested.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Amazon S3 Glacier Deep Archive
Why it's wrong here
Designed for long-term archival, not suitable for 30-day access.
Amazon S3 One Zone-Infrequent Access (S3 One Zone-IA)
Why it's wrong here
Less durable; logs may need cross-AZ resilience.
Amazon S3 Standard
Why it's wrong here
More expensive for infrequent access patterns.
Amazon S3 Standard-Infrequent Access (S3 Standard-IA)
Why this is correct
Cost-effective for infrequently accessed data with rapid access needs.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often choose S3 One Zone-IA (Option B) thinking it is cheaper due to single-AZ storage, but they overlook the durability and availability requirements for logs that may need to be recovered from an AZ failure, and the fact that S3 Standard-IA is actually more cost-effective for this 30-day retention scenario when considering retrieval costs and minimum storage charges.
Detailed technical explanation
S3 Standard-IA charges a per-GB storage fee that is roughly half that of S3 Standard, but adds a per-GB retrieval fee, which is cost-effective when access frequency is low. The 30-day minimum storage duration charge for S3 Standard-IA (and S3 One Zone-IA) means that if you delete objects before 30 days, you still pay for the full 30 days, which aligns perfectly with the 30-day retention requirement. Under the hood, S3 Standard-IA uses the same 99.999999999% durability and 99.99% availability as S3 Standard, but with a different pricing model that penalizes frequent access via retrieval costs.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
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Data Store Management — study guide chapter
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FAQ
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
The correct answer is: Amazon S3 Standard-Infrequent Access (S3 Standard-IA) — Amazon S3 Standard-Infrequent Access (S3 Standard-IA) is the most cost-effective choice for storing semi-structured JSON logs for up to 30 days with infrequent access. It offers low storage cost (compared to S3 Standard) while providing low-latency retrieval and high durability (99.999999999%) across multiple Availability Zones, making it ideal for data that is accessed less frequently but needs immediate availability when requested.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A data engineer needs to store semi-structured JSON files that are accessed infrequently but must be retrievable within minutes. The data is immutable and must be stored cost-effectively. Which AWS service should the engineer use?
easyWhy C: Amazon S3 Standard-IA (Infrequent Access) is designed for data that is accessed less frequently but requires rapid retrieval when needed, with retrieval times in milliseconds. It offers lower storage costs than S3 Standard while maintaining high durability and availability, making it ideal for storing immutable semi-structured JSON files that must be retrievable within minutes. The service is cost-effective for infrequently accessed data because it charges a retrieval fee per GB, but the storage price is significantly lower than standard tiers.
Variation 2. A data engineer needs to store semi-structured JSON files that are accessed infrequently but must be retrievable within minutes. The data should be stored cost-effectively. Which storage solution meets these requirements?
easyWhy C: Option B is correct because S3 Glacier Deep Archive is cost-effective for infrequently accessed data with retrieval within minutes. Wait, Glacier retrieval is minutes to hours, but Deep Archive is 12 hours. Actually S3 Glacier Instant Retrieval is for infrequent access with millisecond retrieval. But the question says 'within minutes', so S3 Glacier Flexible Retrieval (minutes to hours) or S3 Standard-IA (milliseconds). However, Standard-IA is for infrequent but immediate access. The best cost-effective option for infrequent access with retrieval within minutes is S3 Standard-IA. Option A is for frequent access. Option C is for archives with longer retrieval. Option D is for archival with very long retrieval. So Option A is too expensive, C and D have longer retrieval times. Thus B is correct.
Last reviewed: Jun 24, 2026
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