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Data Store Management →hardMultiple ChoiceObjective-mapped

DEA-C01 Data Store Management Practice Question

This DEA-C01 practice question tests your understanding of data store management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company uses Amazon EMR to process large datasets stored in Amazon S3. The cluster uses a transient configuration and stores intermediate data on HDFS. After a job fails due to a spot instance termination, the data engineer needs to rerun the job. What should the engineer do to minimize data loss and cost?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

A
Use a long-running cluster with all on-demand instances to avoid interruptions.
Why wrong: This increases cost significantly and does not address spot interruptions.
B
Configure the cluster with a mix of spot and on-demand instances and set HDFS replication to 3.
This balances cost and reliability; on-demand instances provide stability for HDFS NameNode and critical nodes.
C
Configure the cluster to use EMRFS and store intermediate data in S3.
Why wrong: EMRFS is for persistent data, not intermediate data; writing intermediate data to S3 is slower and more expensive.
D
Increase the HDFS replication factor to 5 and use only spot instances.
Why wrong: Higher replication factor increases storage cost, and using only spot instances risks losing the entire cluster.

Full breakdown with real-world context →

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

✓

Configure the cluster with a mix of spot and on-demand instances and set HDFS replication to 3.

Option B is correct because using a mix of spot and on-demand instances balances cost savings with fault tolerance, while setting HDFS replication to 3 ensures that intermediate data on HDFS survives the loss of a single node (e.g., a terminated spot instance). This allows the job to resume from the last checkpoint or reduce recomputation, minimizing both data loss and cost.

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 a long-running cluster with all on-demand instances to avoid interruptions.
Why it's wrong here
This increases cost significantly and does not address spot interruptions.
✓
Configure the cluster with a mix of spot and on-demand instances and set HDFS replication to 3.
Why this is correct
This balances cost and reliability; on-demand instances provide stability for HDFS NameNode and critical nodes.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure the cluster to use EMRFS and store intermediate data in S3.
Why it's wrong here
EMRFS is for persistent data, not intermediate data; writing intermediate data to S3 is slower and more expensive.
✗
Increase the HDFS replication factor to 5 and use only spot instances.
Why it's wrong here
Higher replication factor increases storage cost, and using only spot instances risks losing the entire cluster.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume storing intermediate data in S3 (EMRFS) is always better for durability, but they overlook that HDFS replication with spot/on-demand mix provides a cheaper, faster recovery for transient cluster workloads without incurring S3 write costs.

Detailed technical explanation

How to think about this question

HDFS replication factor 3 is the default for fault tolerance in a multi-node cluster, ensuring data survives single-node failures. In transient EMR clusters, intermediate data on HDFS is lost when the cluster terminates; using a mix of spot and on-demand instances with replication 3 allows the job to recover from spot interruptions by leveraging YARN’s resource manager to reschedule tasks on remaining nodes. Real-world scenarios often involve large shuffle operations where recomputation is expensive, making this approach critical for cost-effective resilience.

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.

TExam Day Tips

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.

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

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this DEA-C01 question test?

Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Configure the cluster with a mix of spot and on-demand instances and set HDFS replication to 3. — Option B is correct because using a mix of spot and on-demand instances balances cost savings with fault tolerance, while setting HDFS replication to 3 ensures that intermediate data on HDFS survives the loss of a single node (e.g., a terminated spot instance). This allows the job to resume from the last checkpoint or reduce recomputation, minimizing both data loss and cost.

What should I do if I get this DEA-C01 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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This DEA-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 DEA-C01 exam.