The answer is to use Cloud Storage instead of HDFS for data storage and to use Preemptible VMs for transient tasks. Cloud Storage provides virtually unlimited scalability and eliminates the need to manage HDFS replication, while Preemptible VMs drastically reduce costs for fault-tolerant batch jobs that can handle interruptions. On the Google Professional Data Engineer exam, this Dataproc migration from Hadoop considerations question tests your understanding of cloud-native architecture versus lift-and-shift approaches; a common trap is assuming HDFS must be preserved, but Dataproc is designed to work with Cloud Storage as the primary storage layer. Remember that master nodes should always be on-demand for reliability, and the Cloud Storage connector is mandatory for reading data. A useful memory tip is "Storage in the cloud, compute on the cheap"—store data persistently in Cloud Storage and use Preemptible VMs for worker nodes to optimize cost and performance.
PDE Designing data processing systems Practice Question
This PDE practice question tests your understanding of designing data processing systems. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 engineer is migrating on-premises Hadoop jobs to Dataproc. Which TWO considerations are important?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Preemptible VMs for worker nodes to reduce cost
Options A and C are correct: use Cloud Storage instead of HDFS for scalability and cost, and use Preemptible VMs for transient tasks. Option B is wrong because HDFS is not recommended on Dataproc. Option D is wrong because master nodes should be on-demand for reliability. Option E is wrong because Cloud Storage connector is necessary.
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 Preemptible VMs for worker nodes to reduce cost
Why this is correct
Preemptible VMs are cost-effective for fault-tolerant jobs.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use Cloud Storage instead of HDFS for data storage
Why this is correct
Cloud Storage is scalable, durable, and cost-effective, and integrates with Dataproc.
Related concept
Read the scenario before looking for a memorised answer.
✗
Avoid using Cloud Storage connector to prevent overhead
Why it's wrong here
Cloud Storage connector is needed for Dataproc to access Cloud Storage.
✗
Keep HDFS for better performance
Why it's wrong here
HDFS on Dataproc is ephemeral and not recommended; Cloud Storage is preferred.
✗
Use on-demand VMs for master node to ensure availability
Why it's wrong here
Master node should be on-demand for reliability, but this is not a key migration consideration.
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 PDE 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.
Designing data processing systems — This question tests Designing data processing systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Preemptible VMs for worker nodes to reduce cost — Options A and C are correct: use Cloud Storage instead of HDFS for scalability and cost, and use Preemptible VMs for transient tasks. Option B is wrong because HDFS is not recommended on Dataproc. Option D is wrong because master nodes should be on-demand for reliability. Option E is wrong because Cloud Storage connector is necessary.
What should I do if I get this PDE question wrong?
Identify which PDE 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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