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DVA-C02 · Question #290

A developer needs to implement a custom machine learning (ML) library in an application. The size of the library is 15 GB. The size of the library is increasing. The application uses AWS Lambda…

The correct answer is D. Save the library in an Amazon Elastic File System (Amazon EFS) file system. Mount the EFS file. Option D is correct because Amazon EFS can be mounted directly to Lambda functions, supports files far larger than Lambda's limits, and scales automatically as the library grows - making it ideal for a large, expanding 15 GB ML library shared across all functions. Why the…

Submitted by kim_seoul· Mar 5, 2026Development with AWS Services

Question

A developer needs to implement a custom machine learning (ML) library in an application. The size of the library is 15 GB. The size of the library is increasing. The application uses AWS Lambda functions. All the Lambda functions must have access to the library. Which solution will meet these requirements?

Options

  • ASave the library in Lambda layers. Attach the layers to all Lambda functions.
  • BSave the library in Amazon S3. Download the library from Amazon S3 inside the Lambda
  • CSave the library as a Lambda container image. Redeploy the Lambda functions with the new
  • DSave the library in an Amazon Elastic File System (Amazon EFS) file system. Mount the EFS file

How the community answered

(20 responses)
  • B
    5% (1)
  • C
    10% (2)
  • D
    85% (17)

Explanation

Option D is correct because Amazon EFS can be mounted directly to Lambda functions, supports files far larger than Lambda's limits, and scales automatically as the library grows - making it ideal for a large, expanding 15 GB ML library shared across all functions.

Why the distractors fail:

  • A (Lambda Layers): Layers have a hard 250 MB unzipped size limit per function, which is far too small for a 15 GB library.
  • B (S3 download): Downloading 15 GB on every Lambda invocation would be extremely slow, costly, and would exceed Lambda's 512 MB–10 GB ephemeral /tmp storage limit for most configurations - plus it adds significant cold-start latency.
  • C (Container image): Lambda container images support up to 10 GB, still under the 15 GB requirement, and the library would need to be rebaked into a new image every time it grows - not a scalable solution.

Memory tip: Think of EFS as a shared network drive for Lambda - when your dependency is too big to package and needs to be shared across many functions simultaneously, EFS is the go-to. The pattern is: "Big + Shared + Growing = EFS."

Topics

#AWS Lambda#Amazon EFS#Serverless architecture#Lambda deployment options

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