DBS-C01 Management and Operations Practice Question
A company runs a production Amazon RDS for MySQL Multi-AZ DB instance with 10 TB of storage. The application team notices that database write latency has increased from 5 ms to 80 ms over the past week. The DB instance is a db.r5.8xlarge with 500 GB of gp2 storage. CloudWatch metrics show WriteIOPS averaging 10,000, WriteThroughput at 50 MB/s, and BurstBalance decreasing from 100% to 20% over the same period. The DB instance has no reserved IOPS. The database workload is write-heavy with frequent small transactions. The company needs to resolve the high write latency while minimizing costs and downtime. Which solution should the database specialist recommend?
⚠ Common exam trap
AWS often tests the misconception that increasing instance size (vCPUs/memory) resolves storage I/O bottlenecks, when in fact gp2 burst credit exhaustion is a storage-level issue that requires increasing volume size or switching to provisioned IOPS.
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
✓
Modify the DB instance to increase the allocated storage to 1 TB using gp2, allowing the volume to operate with higher baseline IOPS and burst credits.
Increasing gp2 storage from 500 GB to 1 TB raises the baseline IOPS from 1,500 (3 IOPS/GB) to 3,000, and also increases the burst credit pool size. With WriteIOPS averaging 10,000, the volume is depleting burst credits faster than they can be replenished, causing BurstBalance to drop to 20% and latency to spike. Doubling the storage provides a higher baseline and more credits, reducing reliance on burst and resolving the latency issue without changing instance class or adding cost for reserved IOPS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a read replica to offload write traffic to the replica and use it for failover.
Why it's wrong here
Read replicas offload read traffic, not write traffic; write traffic still hits the primary instance, and latency remains.
- ✗
Upgrade the DB instance to a db.r5.16xlarge with more vCPUs and memory to handle higher write throughput.
Why it's wrong here
The bottleneck is storage IOPS, not compute; a larger instance does not increase EBS performance and costs more.
- ✗
Enable Performance Insights to identify slow queries and add database-level caching to reduce write load.
Why it's wrong here
Performance Insights helps with query tuning but does not address the underlying storage I/O limit; caching reduces read load, not write load.
- ✓
Modify the DB instance to increase the allocated storage to 1 TB using gp2, allowing the volume to operate with higher baseline IOPS and burst credits.
Why this is correct
Increasing volume size boosts baseline IOPS and burst balance, resolving the bottleneck without changing instance type.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-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 DBS-C01 exam.