MLS-C01 Data Engineering Practice Question
A data scientist is training a deep learning model on a GPU instance. The training data is stored in S3 and is 50 GB. To reduce I/O bottlenecks, which storage option should be used to cache the data locally on the instance?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Mount an Amazon FSx for Lustre file system linked to the S3 bucket
Amazon FSx for Lustre is a high-performance file system designed for HPC and machine learning workloads. By linking it to the S3 bucket, it automatically caches data locally on the Lustre file system attached to the GPU instance, providing low-latency access and reducing I/O bottlenecks. Option A is incorrect because Amazon EFS is a shared file system with lower throughput compared to Lustre, and it is not optimized for the high throughput needed for deep learning training. Option C is incorrect because while EBS io2 volumes provide high IOPS, copying data using AWS DataSync introduces an extra step and does not provide the seamless caching and high aggregate throughput that FSx for Lustre offers. Option D is incorrect because instance store volumes are ephemeral and not persistent; they would require re-copying the data each time the instance is stopped, and they lack the integration with S3 that FSx for Lustre provides.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Attach an Amazon EFS file system to the instance and copy data from S3
Why it's wrong here
EFS is not designed for high-throughput caching of S3 data.
- ✓
Mount an Amazon FSx for Lustre file system linked to the S3 bucket
Why this is correct
FSx for Lustre provides high throughput and can cache S3 data locally.
- ✗
Provision an Amazon EBS io2 volume and copy data from S3 using AWS DataSync
Why it's wrong here
This adds latency and complexity; not the best for caching.
- ✗
Use instance store volumes to cache the data from S3
Why it's wrong here
Instance store is ephemeral and not reliable for caching.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MLS-C01 exam.