The answer is to use Amazon EMR with S3 as the data store via EMRFS for the best price-performance. This is correct because S3 decouples compute from storage, eliminating the costly 3x replication overhead inherent to HDFS; with EMRFS, Spark reads data directly from S3 with high throughput, and you only pay for the storage you use and the transient compute cluster. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of cost-optimized data lake architectures versus traditional on-premises Hadoop patterns—a common trap is choosing HDFS on EBS, which replicates the 3x overhead and keeps compute tied to storage, driving up costs. Remember the key distinction: HDFS is for ephemeral, local processing, while S3 is the durable, scalable backbone for long-term data. Memory tip: “S3 saves you three times the cost” (no triple replication).
MLS-C01 Data Engineering Practice Question
This MLS-C01 practice question tests your understanding of data engineering. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An organization is migrating its on-premises Hadoop cluster to AWS. The cluster runs Spark jobs that process 50 TB of data daily. The data is stored in HDFS with 3x replication. Which storage option on AWS provides the best price-performance for this workload?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Amazon EMR with S3 as the data store via EMRFS
Amazon EMR with S3 as storage (using EMRFS) allows separating compute and storage. S3 is durable and cost-effective, avoiding 3x replication overhead. HDFS on EBS would require similar replication and is more expensive. S3 with EMR is the standard recommendation.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use AWS Glue to run Spark jobs with data stored in S3
Why it's wrong here
Glue can run Spark, but for large-scale jobs, EMR offers more flexibility and performance tuning.
✓
Use Amazon EMR with S3 as the data store via EMRFS
Why this is correct
S3 provides 11 9's durability and is cheaper than EBS. EMRFS seamlessly integrates with Spark.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Amazon Redshift Spectrum to query the data directly in S3
Why it's wrong here
Redshift is not designed for Spark-based ETL workloads.
✗
Use Amazon EMR with HDFS on EBS volumes
Why it's wrong here
This replicates the on-premises 3x replication cost on EBS, which is expensive.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which MLS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Amazon EMR with S3 as the data store via EMRFS — Amazon EMR with S3 as storage (using EMRFS) allows separating compute and storage. S3 is durable and cost-effective, avoiding 3x replication overhead. HDFS on EBS would require similar replication and is more expensive. S3 with EMR is the standard recommendation.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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