SAA-C03 Design Cost-Optimized Architectures Practice Question
A log archive has old unattached EBS volumes and many stale snapshots. Which two actions reduce storage cost without affecting running instances? The architecture review board prefers a managed AWS-native control.
⚠ Common exam trap
Many candidates confuse stopping instances (which does not delete volumes) with deleting unattached volumes, or they may think disabling CloudTrail reduces storage costs, but CloudTrail logs are stored in S3 and are unrelated to EBS volume or snapshot storage charges.
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
✓
Delete unattached EBS volumes after verifying they are no longer needed
Deleting unattached EBS volumes eliminates storage costs for volumes that are not in use, and since they are not attached to any running instance, this action does not affect running instances. Option D is correct because applying snapshot lifecycle policies (e.g., using Amazon Data Lifecycle Manager) automates the expiration of obsolete snapshots, reducing storage costs without impacting running instances. Both actions are managed AWS-native controls, aligning with the architecture review board's preference.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Stop all EC2 instances in the account
Why it's wrong here
Stopping EC2 instances only transitions them to a stopped state; the underlying EBS volumes remain attached to the instance and continue to incur per-GiB-month charges. To eliminate storage costs, you must either detach and delete the volumes or terminate the instance with the 'Delete on Termination' flag set for root volumes. Simply stopping an instance does not remove volume or snapshot charges, so this option fails to address the stated storage cost issue.
- ✗
Disable CloudTrail logging
Why it's wrong here
Disabling CloudTrail logging would stop recording API activity, but it does nothing to reduce EBS volume or snapshot storage fees, which are billed based on allocated capacity and snapshot data. Audit logs are not part of the EBS storage footprint; turning them off only weakens your ability to detect unauthorized configuration changes and compromises security posture, making it a counterproductive optimization that sacrifices governance without saving storage costs.
- ✓
Delete unattached EBS volumes after verifying they are no longer needed
Why this is correct
Unattached EBS volumes are billed as block storage regardless of whether they are mounted to a running instance. After confirming the volume is not needed for future use or as a boot source, deleting it releases the allocated storage and immediately stops accruing charges. For safety, you can first take a final snapshot, then delete the volume to preserve data recovery options without ongoing volume costs—this directly eliminates the recurring per-GiB-month expense for orphaned volumes.
- ✓
Apply snapshot lifecycle policies to expire obsolete snapshots
Why this is correct
Snapshot lifecycle policies automate the creation, retention, and deletion of EBS snapshots based on age, tag, or count rules. Applying a lifecycle policy that expires obsolete snapshots removes stale backup data and reduces the incremental snapshot storage charges that accumulate as snapshots age. This directly targets snapshot-related costs while preserving the ability to retain recent recoverable backups, complementing the deletion of unattached volumes by addressing the other major EBS cost component.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAA-C03 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 SAA-C03 exam.