Quick Answer
The answer is Amazon S3 and Amazon EMR. S3 replaces HDFS as the scalable, durable storage layer for big data workloads, while Amazon EMR with the EMR File System (EMRFS) allows Spark and interactive SQL queries to access S3 as if it were HDFS, eliminating the need for traditional cluster-attached storage. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of decoupling compute from storage—a core principle for cost-effective, elastic data lakes. A common trap is choosing Amazon FSx for Lustre or EBS, which are high-performance or block storage but lack S3’s 99.999999999% durability and infinite scalability. Remember: for HDFS replacement, think “S3 for storage, EMR for compute”—or use the mnemonic “S3 Stores, EMR Executes.”
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.
A data engineering team is migrating on-premises Hadoop workloads to AWS. The workloads include batch processing using Apache Spark and interactive SQL queries. The data is stored in HDFS. Which TWO AWS services should be used to replace HDFS and provide a scalable, durable storage layer? (Choose TWO.)
Amazon EMR with EMRFS
EMRFS allows EMR to use S3 as a replacement for HDFS.
Amazon S3
Scalable, durable object storage, ideal for data lakes.
Amazon EBS
Why wrong: Block storage, not suitable for large-scale data lakes.
Amazon FSx for Lustre
Why wrong: High-performance file system, but not as durable or cost-effective as S3 for long-term storage.
Amazon RDS
Why wrong: Relational database, not a storage system for Hadoop workloads.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Amazon EMR with EMRFS
Amazon S3 is the primary storage for data lakes, replacing HDFS. Amazon EMR with EMRFS can access S3 as if it were HDFS. Option B (Amazon FSx for Lustre) is a high-performance file system but not a direct HDFS replacement for durability. Option C (Amazon EBS) is block storage, not scalable. Option D (Amazon RDS) is relational database. Option E (Amazon DynamoDB) is NoSQL.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Amazon EMR with EMRFS
Why this is correct
EMRFS allows EMR to use S3 as a replacement for HDFS.
Related concept
Read the scenario before looking for a memorised answer.
Amazon S3
Why this is correct
Scalable, durable object storage, ideal for data lakes.
Related concept
Read the scenario before looking for a memorised answer.
Amazon EBS
Why it's wrong here
Block storage, not suitable for large-scale data lakes.
Amazon FSx for Lustre
Why it's wrong here
High-performance file system, but not as durable or cost-effective as S3 for long-term storage.
Amazon RDS
Why it's wrong here
Relational database, not a storage system for Hadoop workloads.
Common exam traps
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
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.
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FAQ
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
The correct answer is: Amazon EMR with EMRFS — Amazon S3 is the primary storage for data lakes, replacing HDFS. Amazon EMR with EMRFS can access S3 as if it were HDFS. Option B (Amazon FSx for Lustre) is a high-performance file system but not a direct HDFS replacement for durability. Option C (Amazon EBS) is block storage, not scalable. Option D (Amazon RDS) is relational database. Option E (Amazon DynamoDB) is NoSQL.
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.
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
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.
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