MLS-C01 Data Engineering Practice Question
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?
⚠ Common exam trap
A common mix-up: candidates assume HDFS replication is necessary for durability on AWS, overlooking that S3 provides built-in replication and durability, making EMRFS with S3 the cost-effective and performant choice for Spark workloads.
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
✓
Use Amazon EMR with S3 as the data store via EMRFS
Amazon EMR with S3 as the data store via EMRFS provides the best price-performance for this workload because it eliminates the need for 3x replication (S3 is inherently durable and replicated across multiple AZs), reduces storage costs, and allows compute and storage to scale independently. EMRFS enables Spark jobs to read/write directly to S3 with consistency guarantees, matching the throughput requirements of 50 TB daily processing without the overhead of managing HDFS on EBS volumes.
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.
- ✗
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.
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
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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.