DVA-C02 Troubleshooting and Optimization Practice Question
A developer is troubleshooting a slow Amazon RDS for MySQL database. The application experiences high latency on write operations. Which TWO actions can improve write performance?
⚠ Common exam trap
Candidates often mistakenly believe that enabling Multi-AZ (Option E) or adding Read Replicas (Option A) will help with write performance. In reality, Multi-AZ increases write latency due to synchronous replication, and Read Replicas only scale read operations.
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
✓
Increase the allocated storage size to get better I/O performance.
Option B is correct because Amazon RDS storage performance is tied to the allocated storage size: increasing the allocated storage (especially into higher gp2/gp3 or io1/io2 tiers) raises the available IOPS and throughput, which directly reduces write latency. Option D is correct because moving to a larger DB instance class provides more vCPU, memory, and dedicated EBS bandwidth, allowing the database to process write operations faster and relieve resource contention. Option A is not correct because a read replica only offloads read traffic and does not improve write performance on the primary. Option C is not correct because deletion protection is a safety feature that prevents accidental deletion and has no effect on I/O performance. Option E is not correct because Multi-AZ provides high availability via synchronous standby replication, not write performance improvement; in fact, it can add slight write overhead.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a read replica to offload read traffic.
Why it's wrong here
Adding a read replica offloads read-heavy queries from the primary database instance, distributing the read workload across multiple endpoints. However, read replicas do not process write operations; all write traffic must still be directed to and processed by the primary DB instance. Therefore, a read replica will not alleviate performance issues specifically related to slow writes on the primary database.
- ✓
Increase the allocated storage size to get better I/O performance.
Why this is correct
Increasing the allocated storage size, particularly for General Purpose SSD (gp2) volumes, directly improves I/O performance because throughput and IOPS scale with storage capacity. Larger gp2 volumes provide a higher baseline IOPS and accumulate I/O credits faster, enabling sustained burst performance and mitigating I/O bottlenecks. This ensures the database can read and write data to disk more efficiently, which is critical for write-intensive workloads.
- ✗
Enable deletion protection.
Why it's wrong here
Enabling deletion protection is a safety feature that prevents an Amazon RDS DB instance from being accidentally deleted. This configuration setting is purely for operational resilience and data integrity, ensuring that critical databases are not inadvertently removed. It has absolutely no impact on the runtime performance, CPU utilization, memory, or I/O capabilities of the database instance.
- ✓
Increase the DB instance class to a larger size.
Why this is correct
Increasing the DB instance class to a larger size provides more CPU, memory, and often better network bandwidth, which are critical resources for handling write-intensive workloads. More CPU cores allow the database to process transactions and execute queries faster, while increased memory can cache more data, reducing the frequency of slower disk I/O operations. This directly addresses performance bottlenecks stemming from insufficient compute resources.
- ✗
Enable Multi-AZ deployment for high availability.
Why it's wrong here
Enabling Multi-AZ deployment configures a synchronous standby replica in a different Availability Zone for high availability and disaster recovery. While it ensures automatic failover in case of an outage, the primary instance still handles all write operations, and the synchronous replication adds a slight overhead. Multi-AZ does not improve write performance; its purpose is resilience, not performance scaling for write-heavy workloads.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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