The answer is that the gp2 volume size is too small, resulting in insufficient baseline IOPS. This is correct because gp2 storage provides a baseline of 3 IOPS per GB, so a 100 GB volume delivers only 300 baseline IOPS—far too low for sustained write-heavy workloads. When write demand exceeds this baseline, the volume relies on burst credits, but once those credits are exhausted, the volume is throttled, causing high write latency. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of gp2 IOPS limits and the relationship between volume size, baseline performance, and burst credits. A common trap is assuming gp2 always bursts indefinitely or that increasing instance size fixes storage-level latency. Remember the 3-to-1 rule: 3 IOPS per GB for gp2 baseline, and a 100 GB volume gives only 300 IOPS—so for write-heavy RDS MySQL, always check if the volume size is large enough to sustain the required throughput without draining credits.
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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.
Network Topology
Refer to the exhibit. A developer reports that the RDS MySQL instance 'mydb' is experiencing high write latency. The storage is gp2 with 100 GB. What is the MOST likely cause of the write latency?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The gp2 volume size is too small, resulting in insufficient baseline IOPS
The gp2 volume's baseline IOPS are determined by the volume size at a ratio of 3 IOPS per GB, up to 16,000 IOPS. With a 100 GB gp2 volume, the baseline IOPS is only 300 (100 × 3). This is insufficient for write-heavy workloads, causing write latency as the volume exhausts its IOPS credit balance and enters a throttled state. Burst credits can temporarily boost performance, but sustained high write throughput will deplete credits and lead to latency.
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.
✗
There is a read replica causing replication lag
Why it's wrong here
No read replicas are configured.
✓
The gp2 volume size is too small, resulting in insufficient baseline IOPS
Why this is correct
gp2 baseline IOPS is 3 per GB, so 100 GB gives only 300 IOPS.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The instance class db.r5.large does not provide enough memory
Why it's wrong here
Memory affects caching, not directly write latency.
✗
Multi-AZ is not enabled, causing synchronous replication overhead
Why it's wrong here
Multi-AZ is not enabled, so there is no replication overhead.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may overlook the gp2 IOPS-to-size ratio and assume any gp2 volume can burst indefinitely, or they may confuse storage performance issues with instance class or replication factors.
Detailed technical explanation
How to think about this question
gp2 volumes use a credit-based burst model where each volume earns 3 IOPS per GB as baseline, and can burst up to 3,000 IOPS for 30 minutes using accumulated credits. A 100 GB volume has only 300 baseline IOPS, so sustained writes above that threshold will quickly deplete credits, forcing the volume to operate at baseline and causing latency. In contrast, gp3 volumes offer a baseline of 3,000 IOPS regardless of size, making them more suitable for write-intensive workloads without the burst credit limitation.
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 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
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.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The gp2 volume size is too small, resulting in insufficient baseline IOPS — The gp2 volume's baseline IOPS are determined by the volume size at a ratio of 3 IOPS per GB, up to 16,000 IOPS. With a 100 GB gp2 volume, the baseline IOPS is only 300 (100 × 3). This is insufficient for write-heavy workloads, causing write latency as the volume exhausts its IOPS credit balance and enters a throttled state. Burst credits can temporarily boost performance, but sustained high write throughput will deplete credits and lead to latency.
What should I do if I get this DBS-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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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