Question #847
An enterprise operates a database workload that is consistent, long-running, and requires continuous availability without interruptions. Which Amazon EC2 instance purchasing options BEST meet these requirements in the most cost-effective manner? (Choose two.)
On-Demand Instances
Reserved Instances
Spot Instances
Savings Plans
Dedicated Hosts
Explanation
The correct answers are B (Reserved Instances) and D (Savings Plans).
Why B & D are correct:
- Reserved Instances (RIs): Offer significant discounts (up to 72%) for long-term commitments (1-3 years), ideal for consistent, uninterrupted workloads like databases. They reserve capacity, ensuring availability.
- Savings Plans: Provide flexible, usage-based discounts (similar to RIs) for committed hourly spend over 1-3 years. They apply automatically to any instance family/region, offering cost efficiency without capacity management.
Why others are incorrect:
- A (On-Demand): No upfront commitment, but higher costs over time, making it less cost-effective for long-running workloads.
- C (Spot): Unreliable for continuous workloads due to potential interruptions.
- E (Dedicated Hosts): Focuses on hardware isolation/licensing compliance, not cost optimization.
Key Points:
- Use RIs/Savings Plans for predictable, long-term workloads to maximize savings and availability.
- Avoid Spot for mission-critical databases.
- Savings Plans offer flexibility over RIs but require consistent usage.
Answer
The correct answer is: BD