MLS-C01 Data Engineering Practice Question
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.)
⚠ Common exam trap
Watch out — candidates often confuse Amazon EBS or FSx for Lustre as viable HDFS replacements, not realizing that HDFS is a distributed filesystem designed for shared access across many nodes, whereas S3 with EMRFS provides the same semantics with superior durability and scalability.
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
✓
Amazon EMR with EMRFS
Amazon S3 provides a highly durable (99.999999999% durability), scalable, and cost-effective object storage layer that replaces HDFS for Hadoop workloads. Amazon EMR with EMRFS allows Spark and Hive to read and write data directly from S3, treating it as a native filesystem with features like consistent view and read-after-write consistency, making it the ideal compute layer for batch processing and interactive SQL queries.
Answer analysis
Option-by-option breakdown
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.
- ✓
Amazon S3
Why this is correct
Scalable, durable object storage, ideal for data lakes.
- ✗
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.
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.