The answer is to modify the storage type to Provisioned IOPS (io1) with 3000 IOPS. This is correct because a consistently high storage queue depth above 100 indicates that the current general-purpose SSD (gp2) or magnetic storage is bottlenecked, unable to meet the write IOPS demand, which directly causes high write latency. Provisioned IOPS guarantees a dedicated throughput level, eliminating throttling and reducing queue depth by ensuring the storage subsystem can handle the write workload. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your ability to diagnose storage performance issues using queue depth as a key metric—a common trap is confusing queue depth with CPU or memory pressure. Remember: high queue depth plus high write latency equals an IOPS ceiling, not a compute problem. Memory tip: “Queue depth over 100? IOPS must be bought, not burst.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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.
Network Topology
A company is running an Amazon RDS for MySQL instance as shown in the exhibit. The application is experiencing high write latency. The instance has a high number of write operations and the storage queue depth is consistently above 100. Which change would most effectively reduce write latency?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the storage type to Provisioned IOPS (io1) with 3000 IOPS.
The correct answer is A because the instance is experiencing high write latency with a consistently high storage queue depth (above 100), which indicates that the current storage (likely gp2 or magnetic) cannot keep up with the write IOPS demand. Provisioned IOPS (io1) with 3000 IOPS guarantees a dedicated level of IOPS, reducing queue depth and write latency by ensuring the storage subsystem can handle the write workload without throttling.
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.
✓
Modify the storage type to Provisioned IOPS (io1) with 3000 IOPS.
Read the scenario before looking for a memorised answer.
✗
Change the instance class to db.m5.xlarge.
Why it's wrong here
Instance class is not the bottleneck; storage IOPS is.
✗
Enable Multi-AZ to offload writes to a standby.
Why it's wrong here
Multi-AZ is for availability, writes go to primary only.
✗
Increase the allocated storage to 200 GB.
Why it's wrong here
Increasing gp2 storage increases baseline IOPS, but not as effectively as io1.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Multi-AZ replication as a way to distribute write load, but in reality, Multi-AZ only handles failover and read replicas for reads, not writes, and increasing storage or instance size without addressing the IOPS bottleneck will not resolve high queue depth.
Detailed technical explanation
How to think about this question
Under the hood, Amazon RDS for MySQL uses EBS volumes for storage; gp2 volumes provide a baseline of 3 IOPS per GB with bursts up to 3000 IOPS for 30 minutes, but sustained high write operations can exhaust the burst balance, causing throttling and queue buildup. Provisioned IOPS (io1) volumes deliver consistent IOPS regardless of burst credits, making them ideal for write-heavy workloads with queue depths consistently above 100. In real-world scenarios, monitoring the 'WriteLatency' and 'QueueDepth' CloudWatch metrics is critical; if queue depth exceeds 100 and write latency is high, switching to io1 with appropriately provisioned IOPS is the standard remediation.
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: Modify the storage type to Provisioned IOPS (io1) with 3000 IOPS. — The correct answer is A because the instance is experiencing high write latency with a consistently high storage queue depth (above 100), which indicates that the current storage (likely gp2 or magnetic) cannot keep up with the write IOPS demand. Provisioned IOPS (io1) with 3000 IOPS guarantees a dedicated level of IOPS, reducing queue depth and write latency by ensuring the storage subsystem can handle the write workload without throttling.
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.
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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