Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Site Reliability Engineer (SRE).
For SOA-C02 candidates, the confusion often lies in understanding which EC2 purchasing options grant regional flexibility and how commitments affect cost savings. In production, this is about knowing exactly how Reserved Instances differ from Savings Plans in scope and discount applicability. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
CloudNova Technologies operates a fleet of 90 Amazon EC2 instances currently running in the eu-central-1 region. Within the next 8 weeks, CloudNova plans to migrate these workloads to the eu-north-1 region. To optimize costs, the executive team wants to commit to a one-year contract starting next week that will provide discounted prices for these 90 instances regardless of which AWS region they run in during that time.
The Requirement #
Select an EC2 instance purchasing option that will deliver cost savings across regions for a fixed 1-year commitment period starting immediately.
The Options #
- A) Purchase Standard Reserved Instances (RIs) for EC2.
- B) Purchase an EC2 Instance Savings Plan.
- C) Purchase Convertible Reserved Instances (RIs) for EC2.
- D) Purchase a Compute Savings Plan.
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Correct Answer #
D) Purchase a Compute Savings Plan.
Quick Insight: The SOA-C02 Imperative #
- SRE Focus: Understand that Standard and Convertible Reserved Instances are region bound, while Savings Plans (compute type) provide broader regional flexibility for cost savings on compute usage. This flexibility is critical during migrations or scaling workloads across regions.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option D — Purchase a Compute Savings Plan.
The Winning Logic #
- Compute Savings Plans apply to any Amazon EC2 instance usage regardless of region, instance family, or operating system. This means CloudNova’s team can freely migrate their 90 instances from eu-central-1 to eu-north-1 without losing discounts.
- The one-year term commitment aligns perfectly with the requirement to start next week and covers the 12-month period.
- Savings Plans automatically apply discounts based on usage rather than specific instance IDs or regions, simplifying ongoing management during migration.
The Trap (Distractor Analysis): #
- Why not A (Standard Reserved Instances)?
Standard RIs are region-specific and instance-type specific, binding CloudNova to the original region. Discounts would not transfer to eu-north-1, risking costly underutilization after migration. - Why not B (Instance Savings Plan)?
Instance Savings Plans provide flexibility across instance families but are region-bound, so they don’t support cross-region migration discounts. - Why not C (Convertible Reserved Instances)?
Convertible RIs offer instance flexibility but remain tied to a specific region, giving no cost advantage for cross-region migration.
The Technical Blueprint #
# Example CLI command to purchase a Compute Savings Plan for 1 year
aws savingsplans purchase-savings-plan \
--savings-plan-offering-id <compute-plan-offering-id> \
--commitment 43800 # $ per hour commitment (example)
--payment-option AllUpfront \
--term 31536000 # 1 year in seconds
The Comparative Analysis #
| Option | Operational Overhead | Automation Level | Regional Flexibility | Impact on Costs |
|---|---|---|---|---|
| A) Standard RIs | Moderate (tracking RIs per region) | Low | No (region-bound) | High but inflexible |
| B) Instance Savings Plan | Low (usage-based) | High | No (region-bound) | Moderate, less flexible |
| C) Convertible RIs | Moderate | Low | No (region-bound) | Flexible instance types, not region |
| D) Compute Savings Plan | Low | High | Yes (cross-region) | High and flexible |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick Compute Savings Plans if you see cross-region or variable-instance usage during a fixed-term commitment.
Real World #
In practice, companies prefer Compute Savings Plans when planning migrations to new AWS regions or running hybrid workloads because it reduces administrative overhead and cost unpredictability.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the SOA-C02 exam.