DOP-C02 Incident and Event Response Practice Question
A DevOps engineer is troubleshooting an Amazon RDS for PostgreSQL instance that is running out of storage. The engineer wants to resolve the issue without downtime. Which TWO actions can achieve this? (Choose two.)
⚠ Common exam trap
Candidates often confuse instance class scaling (compute/memory) with storage scaling, or mistakenly think that deleting snapshots (which are stored separately in S3) can free up space on the DB instance's attached storage volume.
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
✓
Enable storage auto scaling on the DB instance.
Enabling storage auto scaling on an Amazon RDS for PostgreSQL instance allows the database to automatically increase its allocated storage when it detects that available storage is running low, preventing out-of-storage errors without requiring manual intervention or downtime. Option E is correct because modifying the DB instance to increase the allocated storage size is a dynamic operation that can be performed without downtime, as Amazon RDS supports online storage scaling for PostgreSQL instances, allowing the change to take effect while the database remains available.
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 and promote it to primary.
Why it's wrong here
Creating a read replica and promoting it does not increase the storage capacity of the original DB instance. A read replica is a separate instance that replicates data for read scaling, and promotion simply makes that replica the new primary with the same allocated storage size. The underlying storage-full issue on the original volume remains unresolved, and the promotion process introduces downtime without adding any space to the existing instance.
- ✓
Enable storage auto scaling on the DB instance.
Why this is correct
Enabling storage auto scaling on the DB instance automatically increases the allocated storage when free space falls below the configured threshold, up to your specified maximum. Amazon RDS detects low storage conditions and modifies the storage volume dynamically, requiring no manual intervention or downtime. This is the most direct and proactive solution to prevent the instance from reaching a storage-full state.
- ✗
Delete old automated snapshots to free up storage.
Why it's wrong here
Deleting old automated snapshots does not free up space on the DB instance's allocated storage because automated backups are stored in Amazon S3, not on the instance's EBS volume. The storage-full error is caused by the growth of database files, transaction logs, or temporary files on the primary volume. Additionally, snapshot retention is independent of the instance's storage capacity, so removing them has no impact on available space.
- ✗
Scale up the DB instance to a larger instance class.
Why it's wrong here
Scaling the DB instance to a larger instance class changes the compute and memory resources (CPU and RAM) but does not alter the size of the allocated storage volume. The instance class and the storage allocation are separate dimensions in Amazon RDS, and increasing the former does not expand the latter. Therefore, this action does nothing to resolve the 'insufficient storage' condition and may incur unnecessary costs without addressing the root cause.
- ✓
Modify the DB instance to increase the allocated storage size.
Why this is correct
Modifying the DB instance to increase the allocated storage size directly expands the EBS volume capacity, giving the database more space to grow. This change can be performed as a dynamic modification for most General Purpose SSD and Provisioned IOPS storage, typically with minimal downtime and without a reboot. It is a valid corrective action, though it requires manual monitoring and setting the new size, unlike storage auto-scaling which handles it automatically.
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Same concept, more angles
1 more way this is tested on DOP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An Amazon RDS for PostgreSQL instance is running low on storage. The DevOps engineer needs to increase the allocated storage without downtime. Which action should be taken?
easy- A.Modify the DB instance to a larger instance class.
- ✓ B.Modify the DB instance to increase the allocated storage.
- C.Create a snapshot of the DB instance and restore it with larger storage.
- D.Launch a new read replica with larger storage and promote it.
Why B: Amazon RDS supports storage autoscaling and manual storage scaling by modifying the DB instance's allocated storage. Increasing allocated storage is an online operation that does not require downtime; RDS handles the underlying volume expansion transparently. This is the correct action to increase storage without downtime.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DOP-C02 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 DOP-C02 exam.