Cost-Optimized S3 Lifecycle for Small Files Migration

SAA-C03 By islever Editorial Last updated

Design cost-optimized storage solutions.

Short answer

A Group small files into large objects to avoid 128 KB minimum charges, then use lifecycle policies to move them from Glacier Instant Retrieval to Deep Archive.

Question

A company is using AWS DataSync to migrate millions of files from an on-premises system to AWS. The files are 10 KB in size on average. The company wants to use Amazon S3 for file storage. For the first year after the migration, the files will be accessed once or twice and must be immediately available. After 1 year, the files must be archived for at least 7 years. Which solution will meet these requirements MOST cost-effectively?
  1. Use an archive tool to group the files into large objects. Use DataSync to migrate the objects. Store the objects in S3 Glacier Instant Retrieval for the first year. Use a lifecycle configuration to transition the files to S3 Glacier Deep Archive after 1 year with a retention period of 7 years. Correct Answer
  2. Use an archive tool to group the files into large objects. Use DataSync to copy the objects to S3 Standard-Infrequent Access (S3 Standard-IA). Use a lifecycle configuration to transition the files to S3 Glacier Instant Retrieval after 1 year with a retention period of 7 years.
  3. Configure the destination storage class for the files as S3 Glacier Instant Retrieval. Use a lifecycle policy to transition the files to S3 Glacier Flexible Retrieval after 1 year with a retention period of 7 years.
  4. Configure a DataSync task to transfer the files to S3 Standard-Infrequent Access (S3 Standard-IA). Use a lifecycle configuration to transition the files to S3 Deep Archive after 1 year with a retention period of 7 years.

Key Takeaways

The exam tests the ability to identify that storing millions of 10 KB files directly in any S3 class incurs a 128 KB minimum charge per file; grouping them into larger objects is required to achieve true cost-effectiveness.

This question addresses the cost-effective migration of millions of small (10 KB) files to Amazon S3 using DataSync and lifecycle policies, highlighting the critical impact of minimum object billing sizes on storage costs.

Common mistake: Most candidates select Option D because they ignore the 10 KB file size constraint, failing to realize that S3 Standard-IA would bill each 10 KB file as 128 KB, resulting in massive unnecessary costs compared to grouped objects.

Expert Analysis

Why the Answer Is Correct

Option A is the correct answer because it addresses the specific economic trap of the scenario: millions of 10 KB files. Amazon S3 bills with a minimum object size of 128 KB for most storage classes (including Standard-IA and Glacier Instant Retrieval). If you store millions of 10 KB files individually, you pay for 128 KB per file, which is over 12x the actual data volume. By using an archive tool to group these small files into large objects (e.g., combining thousands of 10 KB files into a single 1 MB or larger archive), you eliminate this overhead. You then store these efficient large objects in S3 Glacier Instant Retrieval for the first year (meeting the 'immediately available' requirement at a lower cost than Standard-IA for rarely accessed data) and transition them to Glacier Deep Archive after one year for long-term retention.

Why the Other Options Are Wrong

Option B suggests using S3 Standard-IA for the first year. While valid for infrequent access, it still suffers from the 128 KB minimum charge if files are not grouped, and Standard-IA is generally more expensive than Glacier Instant Retrieval for data accessed only 1-2 times a year. Option C configures DataSync to store files directly as S3 Glacier Instant Retrieval without grouping. This results in the same 128 KB minimum charge penalty for each 10 KB file, making it highly inefficient. Option D uses S3 Standard-IA without grouping. As noted by community members like Mistwalker and FlyingHawk, "Each file is 10 KB... S3 charges a minimum of 128 KB per object," leading to "insane unnecessary cost." DataSync can handle small files, but the storage class choice combined with the lack of grouping makes D costly.

Community Comment Notes

The community was split between A and D. Many users, such as dhewa and jfedotov, correctly identified that Option D ignores the operational and financial overhead of small files, stating that "A is not correct" is wrong and "D simplifies the process" is a trap. User Mistwalker highlighted the core issue: "10KB/file x millions of files = insane unnecessary cost when each is charged at 128KB/object." User FlyingHawk provided the detailed math regarding minimum object sizes. Users like blehbleh and Ez1tap supported A, noting that grouping is necessary to avoid the minimum charge penalty and that separate lifecycle policies are needed for the two phases.

Official Reference

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

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

Exam Strategy

Always check the object size and count in S3 cost questions. If the question specifies 'millions of small files' (e.g., < 128 KB), look for options that involve 'grouping', 'archiving', or 'bundling' files before storage to avoid the 128 KB minimum billable unit. Never assume DataSync alone solves the cost problem; the destination storage strategy matters most.

Frequently Asked Questions

Why not just use S3 Standard-IA for the first year?

Standard-IA has a higher storage price than Glacier Instant Retrieval for rarely accessed data. More importantly, without grouping, both incur the 128 KB minimum charge, making them equally inefficient for small files.

Does DataSync automatically group small files?

No. DataSync transfers files as they are. To optimize cost for millions of small files, you must pre-process them into larger archives using external tools before or during migration.

More SAA-C03 FAQ →

Community Votes

A
55%
D
45%

55% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 18 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 18

  1. dhewa 👍 11 Answered D
    D simplifies the process by directly using S3 Standard-IA and then transitioning to S3 Glacier Deep Archive, which aligns well with access patterns and cost requirements. Option A sounds right but using an archive tool to group files into large objects adds complexity and operational overhead. This step isn’t necessary if you can directly manage the files with S3 lifecycle policies.
  2. blehbleh 👍 5 Answered A
    Its A, took some research but A is correct Per Amazon S# glacier page: "Amazon S3 Glacier Instant Retrieval is an archive storage class that delivers the lowest-cost storage for long-lived data that is rarely accessed and requires retrieval in milliseconds. With S3 Glacier Instant Retrieval, you can save up to 68% on storage costs compared to using the S3 Standard-Infrequent Access (S3 Standard-IA) storage class, when your data is accessed once per quarter." After the one year move it to Deep archive.
  3. Ez1tap 👍 4 Answered A
    correct answer is A you need 2 separate lifecycle policy
  4. Abhiiinav 👍 3 Answered D
    answer is D. Storing the objects in S3 Glacier Instant Retrieval for the first year is more expensive than S3 Standard-IA for data that is accessed infrequently.
  5. FlyingHawk 👍 2 Answered A
    - Each file is 10 KB in size. - S3 charges a minimum of 128 KB per object. -Total number of files: millions of files. - Files are accessed twice in the first year. - After 1 year, files are archived for 7 years - S3 Glacier: Minimum charge for 40 KB per object. S3 Standard-IA and S3 One Zone-IA storage have a minimum billable object size of 128 KB. Smaller objects may be stored but will be charged for 128 KB of storage at the appropriate storage class rate Option D does not group those files into big object, so 1 million files will be charged as 1 million objects(128KB). https://aws.amazon.com/s3/pricing/
Show 13 more comments
  1. Mistwalker 👍 2 Answered A
    10KB/file x millions of files = insane unnecessary cost when each is charged at 128KB/object No one is talking about operational overhead, they just want cost-effectiveness
  2. EllenLiu 👍 2 Answered A
    S3 Glacier Instant Retrieval is more expensive than S3 Standard-IA for the first year when immediate availability is required.
  3. nebajp 👍 2 Answered A
    Correct Answer is A Glacier Deep Archive - For long term achieving Glacier Instant Retrieval - Availability for once or twice
  4. jfedotov 👍 2 Answered D
    D is correct. A is not correct, because Amazon S3 Glacier Instant Retrieval min object size is 128KB, in question 10KB
  5. dragossky 👍 2 Answered A
    For sure A, has amazing retrieval - Store the objects in S3 Glacier Instant Retrieval
  6. AMEJack 👍 2 Answered D
    There is no need to use archive tool to migrate small files, DataSync is enough.
  7. progounick 👍 2 Answered A
    ChatGPT agrees with me and selected A
  8. LeonSauveterre 👍 1 Answered D
    About option A: For data stored in the S3 Glacier Instant Retrieval storage class, there is indeed a minimum object size of 128 KB. If the objects are smaller than 128 KB, AWS still charges for 128 KB per object, which can significantly impact cost efficiency when dealing with a large number of small files, such as the 10 KB files in the given scenario. One more thing: once or twice a year is perfect for Infrequent Access. It also provides instant availability for the objects stored in it.
  9. ad2dj28 👍 1 Answered D
    10/10 TIMES STANDARD INFREQUENT ACCESS IS CHEAPER THAN USING GLACIER INSTANT RETRIEVAL WHEN COMPARING COSTS WITH PRICING CALCULATOR
  10. Abdullah2004 👍 3 Answered D
    D is most cost effective
  11. muhammadahmer36 👍 2 Answered A
    Answer is A
  12. tch 👍 1 Answered A
    B & C are out
  13. komorebi 👍 1 Answered B
    Answer is B

Reader comments & corrections

No reader corrections yet — spotted an error or have a note? Share it below.

Log in to comment, report an error, or add a note about this question.

Submitted for moderation before publishing. Keep it helpful and respectful.

S3 Multi-Region Access Point and Replication Strategy

S-grade

Securing NLB with Security Groups for Minimal Change

S-grade

Most Cost-Effective 7-Year Retention for EBS Snapshots?

S-grade

AWS Forecast vs SageMaker for Time-Series Prediction

S-grade

Practice All SAA-C03 Questions

Access 120 questions with complete answers and detailed explanations.

View Full SAA-C03 Practice Test →

← Back to SAA-C03 Study Guide