Reducing cross-Region S3 upload lag by using regional buckets and replication

SAP-C02 By islever Editorial Last updated

Design a solution to meet performance objectives.

Short answer

C Place a regional S3 bucket in each new Region for fast local uploads and replicate to the central eu-north-1 bucket via Cross-Region Replication.

Question

A company runs a highly available data collection application on Amazon EC2 in the eu-north-1 Region. The application collects data from end-user devices and writes records to an Amazon Kinesis data stream and a set of AWS Lambda functions that process the records. The company persists the output of the record processing to an Amazon S3 bucket in eu-north-1. The company uses the data in the S3 bucket as a data source for Amazon Athena. The company wants to increase its global presence. A solutions architect must launch the data collection capabilities in the sa-east-1 and ap-northeast-1 Regions. The solutions architect deploys the application, the Kinesis data stream, and the Lambda functions in the two new Regions. The solutions architect keeps the S3 bucket in eu-north-1 to meet a requirement to centralize the data analysis. During testing of the new setup, the solutions architect notices a significant lag on the arrival of data from the new Regions to the S3 bucket. Which solution will improve this lag time the MOST?
  1. In each of the two new Regions, set up the Lambda functions to run in a VPC. Set up an S3 gateway endpoint in that VPC.
  2. Turn on S3 Transfer Acceleration on the S3 bucket in eu-north-1. Change the application to use the new S3 accelerated endpoint when the application uploads data to the S3 bucket.
  3. Create an S3 bucket in each of the two new Regions. Set the application in each new Region to upload to its respective S3 bucket. Set up S3 Cross-Region Replication to replicate data to the S3 bucket in eu-north-1. Correct Answer
  4. Increase the memory requirements of the Lambda functions to ensure that they have multiple cores available. Use the multipart upload feature when the application uploads data to Amazon S3 from Lambda.

Key Takeaways

When the central bucket's Region lacks Transfer Acceleration support, placing a regional S3 bucket in each ingest Region and replicating to the central bucket removes the long-distance upload path and is the lowest-latency approach.

A globally expanded app keeps its analysis S3 bucket in eu-north-1 while ingesting from sa-east-1 and ap-northeast-1, causing upload lag. Because S3 Transfer Acceleration is unsupported in eu-north-1, the fix is regional buckets in each new Region for fast local uploads plus Cross-Region Replication to the central bucket.

Common mistake: Choosing S3 Transfer Acceleration (Option B) — it is not supported in eu-north-1, so it cannot improve the lag for this centralized bucket.

Expert Analysis

Why the Answer Is Correct

Option C creates an S3 bucket in each new Region so the application uploads locally at low latency, then uses Cross-Region Replication (CRR) to consolidate data into the eu-north-1 analysis bucket. This eliminates the cross-continent upload path that caused the lag.

Why the Other Options Are Wrong

Option B (Transfer Acceleration) is invalid because acceleration is not supported in eu-north-1. Option A (VPC endpoint) reduces intra-Region VPC egress cost but does nothing for cross-Region latency. Option D (more Lambda memory, multipart) marginally speeds a single upload but does not address the geographic distance.

Community Comment Notes

wyeedh1 (likes 18) confirms S3 Transfer Acceleration is unsupported in eu-north-1, ruling out B. VerRi notes that uploading to a same-Region bucket is faster than accelerating the upload to a distant bucket. The community vote is C (68) over B (32).

Official Reference

https://docs.aws.amazon.com/AmazonS3/latest/userguide/replication.html

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

Community Votes

C
68%
B
32%

68% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 27 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 27

  1. wyeedh1 👍 18 Answered C
    s3 transfer acceleration is not supported in eu-north-1 region yet https://docs.aws.amazon.com/AmazonS3/latest/userguide/transfer-acceleration.html
  2. VerRi 👍 7 Answered C
    "improve this lag time the MOST" means improve the time for "uploading files" not "uploading the files to the destination." Uploading the files to the bucket in the same region is faster than transferring them to other regions.
  3. bjexamprep 👍 6 Answered C
    S3 Transfer Acceleration achieves acceleration by AWS routing traffic to AWS cloudfront edge location and transfer aws network backbone. The key speed improvement is AWS network backbone. While, in this case, the application in the two new regions is the client to write the output to S3 in EU, which means the client is already on AWS, the data transportation is already on AWS network backbone. So S3 Transfer Acceleration is not helping at all. B is out. C is the best answer.
  4. leliodesouza 👍 4 Answered C
    Correct Answer is C. S3 transfer acceleration is not yet supported in the eu-north-1 region, as wyeedh1 commented. https://docs.aws.amazon.com/AmazonS3/latest/userguide/transfer-acceleration.html
  5. cf9e355 👍 4 Answered B
    as they said "The solutions architect keeps the S3 bucket in eu-north-1 to meet a requirement to centralize the data analysis". So, B should be the answer
Show 22 more comments
  1. HunkyBunky 👍 4 Answered C
    Answer is C - this option will provide MOST lag-improve solution for application
  2. kejam 👍 4 Answered B
    https://aws.amazon.com/s3/transfer-acceleration/
  3. thotwielder 👍 3 Answered B
    A: wrong. for s3 gateway endpoint it's not possible to access the S3 buckets from another VPC/Region B: typical scenario for s3 transfer acceleration. C: possible. But extra steps. And not sure s3 replication will be faster. So is wrong. D: wrong.
  4. seetpt 👍 3 Answered C
    I would choose B but it cannot be B because S3 Transfer Acceleration is not supported in eu-north-1. This leaves C as the only viable option.
  5. 07c2d2a 👍 2
    B. It's not efficient to upload to 1 S3 bucket, then have it replicated across. It will be faster to use acceleration to get to the actual destination bucket. Additionally, they don't need 2 extra copies of all the data. B makes the most sense from all perspectives.
  6. AloraCloud 👍 2
    Except if RTC is enabled you cannot guarantee that the data replicated to the central S3 bucket in eu-north-1 will be up to date. I'll be dammed if AWS is really expecting folks to remember the regions which do not have the Amazon S3 Transfer Acceleration feature.
  7. veyisceylan 👍 2
    I think that the LAG 7is caused due to network path running to S3 public interfaces. The gateway endpoint can enchance the network path and reduce the LAG. https://aws.amazon.com/blogs/architecture/reduce-cost-and-increase-security-with-amazon-vpc-endpoints/
  8. AloraCloud 👍 2
    I think the answer is C because Amazon Kinesis Data Streams cannot directly leverage S3 Transfer Acceleration. S3 Transfer Acceleration is typically used for accelerating transfers from clients to S3 and doesn't support Kinesis Data Streams directly.
  9. e4bc18e 👍 2
    Answer is C but feel this is one they definitely want people to get wrong. No one is going to memorize which regions every feature is supported in, it is something anyone would look up.
  10. Syre 👍 2 Answered B
    While C would work, it adds complexity by requiring separate S3 buckets in each Region and replicating data, which could increase cost and delay due to replication schedules.
  11. trungtd 👍 2 Answered C
    No matter how fast you run, you cannot run from Tokyo to Stockholm as fast as someone 10km from Stockholm.
  12. sat2008 👍 2 Answered B
    I agree for the reason "requirement to centralize the data analysis" we cant have S3 s in other regions
  13. 0b43291 👍 1 Answered C
    By implementing Option C, the company can leverage the proximity of local S3 buckets in each Region, while still maintaining a centralized data store in eu-north-1 through Cross-Region Replication. This approach minimizes the lag time for data arrival and ensures that the data analysis in Amazon Athena is performed on the complete and up-to-date dataset. The other options have limitations or may not address the lag time issue effectively: Option A (VPC and S3 gateway endpoint) does not directly address the latency issue caused by the long distances between Regions. Option B (S3 Transfer Acceleration) can improve transfer speeds but may not be as effective as having local S3 buckets in each Region. Option D (increasing Lambda memory and using multipart uploads) may improve Lambda performance but does not address the underlying network latency issue.
  14. AzureDP900 👍 1
    Considering the current limitations of S3 Transfer Acceleration in the eu-north-1 Region, I would say that Option C is actually the best choice.
  15. itsjunukim 👍 1 Answered B
    "keeps the S3 bucket in eu-north-1 to meet a requirement to centralize the data analysis" B
  16. TheCloudGuruu 👍 3 Answered B
    B. Transfer Accelertation
  17. qaz12wsx 👍 3 Answered C
    agree with bjexamprep
  18. alexis123456 👍 3
    Correct Answer is C
  19. failexamonly 👍 3 Answered C
    see wyeedh1 answer
  20. career360guru 👍 3 Answered B
    Option B
  21. arberod 👍 3 Answered B
    It is B
  22. akiakiaki 👍 2 Answered C
    wyeedh1

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