S3 Lifecycle Policy Cost Optimization with High Availability

DEA-C01 By islever Editorial Last updated

Choose a data store. Automate data processing by using AWS services.

Short answer

C Transition objects to S3 Standard-Infrequent Access after 6 months and transfer to S3 Glacier Deep Archive after 2 years to meet high availability and maximum cost-effectiveness.

Question

A company currently stores all of its data in Amazon S3 by using the S3 Standard storage class.
A data engineer examined data access patterns to identify trends. During the first 6 months, most data files are accessed several times each day. Between 6 months and 2 years, most data files are accessed once or twice each month. After 2 years, data files are accessed only once or twice each year.
The data engineer needs to use an S3 Lifecycle policy to develop new data storage rules. The new storage solution must continue to provide high availability.
Which solution will meet these requirements in the MOST cost-effective way?
  1. Transition objects to S3 One Zone-Infrequent Access (S3 One Zone-IA) after 6 months. Transfer objects to S3 Glacier Flexible Retrieval after 2 years.
  2. Transition objects to S3 Standard-Infrequent Access (S3 Standard-IA) after 6 months. Transfer objects to S3 Glacier Flexible Retrieval after 2 years.
  3. Transition objects to S3 Standard-Infrequent Access (S3 Standard-IA) after 6 months. Transfer objects to S3 Glacier Deep Archive after 2 years. Correct Answer
  4. Transition objects to S3 One Zone-Infrequent Access (S3 One Zone-IA) after 6 months. Transfer objects to S3 Glacier Deep Archive after 2 years.

Key Takeaways

The main trap is confusing 'high availability' with 'fast retrieval'. S3 Glacier Deep Archive is the cheapest option and satisfies availability requirements even with slow retrieval times.

This question tests selecting the most cost-effective Amazon S3 storage classes for varying access patterns while maintaining high availability. The correct solution uses S3 Standard-IA and S3 Glacier Deep Archive.

Common mistake: Choosing Option B (Glacier Flexible Retrieval) because candidates prioritize faster retrieval times over the explicit instruction to find the MOST cost-effective solution.

Expert Analysis

The question requires a cost-effective storage lifecycle that maintains high availability. The access pattern shifts from frequent (first 6 months) to infrequent monthly (6 months–2 years) to annual (after 2 years).

The most attractive but wrong answer is B (S3 Standard-IA then Glacier Flexible Retrieval). This option seems correct because Glacier Flexible Retrieval offers retrieval times ranging from minutes to hours, which feels more 'responsive' than Deep Archive. Many candidates choose B assuming that 'high availability' implies quick accessibility or that the slight cost difference isn't worth waiting for data. However, the question explicitly asks for the MOST cost-effective way and only mandates high availability, not low-latency retrieval. S3 Standard-IA provides 99.9% availability across multiple Availability Zones, satisfying the HA requirement while being cheaper than Standard for infrequent access.

The deciding factor lies in the final tier. After 2 years, data is accessed only once or twice a year. S3 Glacier Deep Archive is the lowest-cost storage class available on AWS, specifically designed for long-term retention with minimal access frequency. While it has longer retrieval times (12+ hours), the question does not impose a retrieval time constraint. Therefore, choosing Glacier Flexible Retrieval (Option B) incurs unnecessary costs compared to Deep Archive (Option C). Options A and D are incorrect because S3 One Zone-Infrequent Access (One Zone-IA) stores data in a single Availability Zone, offering only 99.5% availability and risking data loss if that zone fails, which violates the high availability requirement.

Thus, transitioning to S3 Standard-IA at 6 months and to S3 Glacier Deep Archive at 2 years provides the optimal balance of multi-AZ durability/availability and minimum cost.

Official Reference

https://aws.amazon.com/s3/storage-classes/

This link opens the official vendor documentation in a new tab.

Exam Strategy

When asked for the 'most cost-effective' solution, always select the lowest-price storage class that meets the non-negotiable constraints (like durability or availability). Do not upgrade to a more expensive class (like Glacier Flexible Retrieval) unless a specific performance constraint (like retrieval time) is explicitly stated in the question.

Frequently Asked Questions

Does S3 Glacier Deep Archive provide high availability?

Yes, S3 Glacier Deep Archive offers 99.999999999% (11 nines) durability. While it stores data in a cost-optimized manner, it still meets the high availability and durability standards required by the question.

Why is S3 One Zone-IA incorrect for this question?

S3 One Zone-IA stores data in a single Availability Zone. If that AZ fails, the data is lost. It offers 99.5% availability, which is lower than the 99.9% offered by S3 Standard-IA and does not meet the 'high availability' requirement as robustly as multi-AZ options.

More DEA-C01 FAQ →

Community Votes

C
59%
B
41%

59% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 46 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 30 of 46

  1. helpaws 👍 22 Answered B
    "S3 Glacier Flexible Retrieval delivers low-cost storage, up to 10% lower cost (than S3 Glacier Instant Retrieval), for archive data that is accessed 1-2 times per year and is retrieved asynchronously" Source: https://aws.amazon.com/s3/storage-classes/glacier/
  2. WarPig666 👍 11 Answered C
    Flexible retrieval will be higher cost than deep archive. If records only need to be retrieved once or twice a year, this doesn't mean they need to be instantly available.
  3. sam_pre 👍 8
    High availability and fast retrieval are two different things
  4. GiorgioGss 👍 4 Answered C
    The new storage solution must continue to provide high availability = A and C out. After 2 years, data files are accessed only once or twice each year. && MOST cost-effective way = C. C is more cost-effective than B.
  5. lucas_rfsb 👍 4 Answered C
    Since it was requested high availability, then can't be Standard One Zone. And in the end of 2 years it was asked for the most cost effective, than Glacier Deep Archive.
Show 25 more comments
  1. ttpro1995 👍 4
    The requirement does not state how fast data need to be retrieval. So, pick Glacier deep for even more cost saving.
  2. altonh 👍 4 Answered C
    There is no requirement for the retrieval time. So this is more cost-effective.
  3. Udyan 👍 3 Answered C
    Is it mentioned in question that Retrieval time is constraint, no, so, if any engineer need to access data, say May and November, so he/she can wait for 2-3 days to get data, as in the long run, they have an year to analyze the data so, deep archive will save costs only.
  4. michele_scar 👍 3 Answered C
    It's C, the request is about "High availability" not "Less time to retrieve the data". The other request is "most cost effective" so deleting A and D for the HA, remains B and C that both satisfy the HA. Now choose the most cost effective --> C
  5. TonyStark0122 👍 3
    Option B: Transition objects to S3 Standard-Infrequent Access (S3 Standard-IA) after 6 months. Transfer objects to S3 Glacier Flexible Retrieval after 2 years.
  6. Udyan 👍 3 Answered C
    This question was in Stephen Maarek Udemy practice questions too, here concern not given for extraction time so, just see cost friendlyness, thus, C over B
  7. iamwatchingyoualways 👍 3 Answered C
    No instant access is mentioned. Most Cost effective.
  8. Nickalodeon99 👍 2 Answered C
    Question says: 1) After 2 years, data files are accessed only once or twice each year. 2) The new storage solution must continue to provide high availability. 3) MOST cost-effective way? S3 Glacier Flexible Retrieval -For archive data that is accessed 1—2 times per year and is retrieved asynchronously (not occurring at the same time). -Retrieval option from 1 minute to 12 hours. -$0.0036 per GB / Mo -S3 Glacier Deep Archive -Data that may be accessed once or twice in a year. -Designed to deliver 99.99% availability -Retrieval time within 12 hours -$0.00099 per GB / Mo I think its Option C, because question is not asking for exact retrieval time but asking most cost effective which is (S3 Glacier Deep Archive). https://aws.amazon.com/s3/storage-classes/?nc=sn&loc=3#topic-5 https://aws.amazon.com/s3/pricing/
  9. truongnguyen86 👍 2 Answered B
    Option B is the correct answer because it balances cost-effectiveness and availability: S3 Standard-IA offers cost savings for infrequently accessed data while maintaining high availability across multiple zones. S3 Glacier Flexible Retrieval is a good balance for archiving with occasional access needs.
  10. anonymous_learner_2 👍 2 Answered C
    Glacier deep archive has the same availability as flexible retrieval and there's no retrieval time requirement so C is the most cost effective that meets the requirements.
  11. blackgamer 👍 2 Answered C
    The question mention "the most cost-effective way". C is most cost-effective and still highly available. The requirement doesn't indicate the retrieval time requirement.
  12. LR2023 👍 2
    questions doesnt provide clairty on when data is accessed does it need to made available instantly or not. Deep archive times are longer.
  13. andrologin 👍 2 Answered B
    Based on this link https://aws.amazon.com/s3/storage-classes/glacier/ Glacier Flexible Retrieval is cheaper that Instant Retrieval
  14. arvehisa 👍 2 Answered C
    2 requirements: 1)highly available 2) cost-effective. no mention about load time so C is correct.
  15. Just_Ninja 👍 2 Answered C
    HA and cost effective. Here is no hint in the question for instant access..
  16. jk15997 👍 2 Answered C
    There is no requirement for the retrieval time.
  17. luigiDDD 👍 2 Answered C
    C is the most cost effective
  18. CalvinL4 👍 2
    Will go with B.
  19. sachin 👍 1
    • S3 Glacier Instant Retrieval delivers the lowest cost storage, up to 68% lower cost (than S3 Standard-Infrequent Access), for long-lived data that is accessed once per quarter and requires millisecond retrieval. • S3 Glacier Flexible Retrieval delivers low-cost storage, up to 10% lower cost (than S3 Glacier Instant Retrieval), for archive data that is accessed 1-2 times per year and is retrieved asynchronously. • S3 Glacier Deep Archive delivers the lowest cost storage, up to 75% lower cost (than S3 Glacier Flexible Retrieval), for long-lived archive data that is accessed less than once per year and is retrieved asynchronously.
  20. Rpathak4 👍 1 Answered C
    Why Not the Other Options? A. S3 One Zone-IA → Glacier Flexible Retrieval ❌ One Zone-IA is risky (data loss if the AZ fails). Glacier Flexible Retrieval is more expensive than Deep Archive. B. S3 Standard-IA → Glacier Flexible Retrieval ❌ Glacier Flexible Retrieval is not the cheapest long-term storage. Deep Archive costs much less. D. S3 One Zone-IA → Glacier Deep Archive ❌ One Zone-IA lacks high availability (single AZ failure = data loss). S3 Standard-IA is safer.
  21. lsj900605 👍 1 Answered B
    B High availability means the need for readily available service. S3 Standard-IA deliver 99.9% availability vs S3 One Zone-IA deliver 99.5% availability S3 Glacier Flexible Retrieval has configurable retrieval times, from minutes to hours, with free bulk retrievals. But with S3 Glacier Deep Archive it's retrieval time is within 12 hours https://aws.amazon.com/s3/storage-classes/
  22. Deno_Dennis 👍 1 Answered C
    Transition objects to S3 Standard-Infrequent Access (S3 Standard-IA) after 6 months because between 6 months and 2 years, most data files are accessed once or twice each month. Transfer objects to S3 Glacier Deep Archive after 2 years because after 2 years, data files are accessed only once or twice each year. This is the most cost-effective approach.
  23. Fexo 👍 1 Answered B
    Answer is B, because Object needs to be retrieved once / twice monthly , hence GFR S3 Glacier Flexible Retrieval delivers low-cost storage, up to 10% lower cost (than S3 Glacier Instant Retrieval), for archive data that is accessed 1-2 times per year and is retrieved asynchronously https://aws.amazon.com/s3/storage-classes/glacier/
  24. Khooks 👍 1 Answered C
    Answer should be C. B: While this option transitions to S3 Glacier Flexible Retrieval after 2 years, which provides quicker retrieval times than Glacier Deep Archive, it is more expensive. Given the infrequent access pattern after 2 years, the additional cost is not justified.
  25. shammous 👍 1 Answered B
    To retrieve data from the S3 Glacier Deep Archive, you need more than 12 hours! The scenario mentions that we still need to access data instantly once or twice yearly. S3 Glacier Flexible Retrieval is more appropriate in this case.

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