AWS — Amazon EC2 Instance Purchasing Options

Overview of AWS EC2 Instance Purchasing Options.

TL;DR:

1. On-Demand Instances: short workload, predictable pricing.
2. Reserved Instances: long workloads (≥ 1 year).
3. Convertible Reserved Instances: long workloads with flexible instances.
4. Scheduled Reserved Instances: launch within time window you reserve.
5. Spot Instances: short workloads, for cheap, can lose instances.
6. Dedicated Instances: no other customers will share your hardware.
7. Dedicated Hosts: book an entire physical server, control instance placement.

On-Demand Instances

• Pay for what you use (Pay, by the second)
• No upfront payment
• No long term commitment
• Recommended for short-term and uninterrupted workloads, where you can’t predict how the application will behave.

Reserved Instances

• Up to 75% discount compared to On-demand
• Pay upfront for what you use with long term commitment
• Reservation period can be 1 or 3 years
• Reserve a specific instance type
• Reserve a specific region
• Recommended for steady state usage applications

Convertible Reserved Instance

• Can change the EC2 instance type
• Up to 54% discount

Scheduled Reserved Instances (Scheduled Instances)

• Purchase instances that are always available on the specified recurring schedule, for a one-year term.
• Launch within time window you reserve
• When you require a fraction of day/week/month
• Pay for the time that the instances are scheduled
• Recommended for an application that runs during business hours or for batch processing that runs at the end of the week

Spot Instances

• Request unused EC2 instances, which can reduce your Amazon EC2 costs significantly.
• Can get a discount of up to 90% compared to On-demand.
• You bid a price and get the instance as long as its under the price
• Price varies based on offer and demand.
• Spot instances are reclaimed with a 2-minute notification warning when the spot price goes above your bid.
• Recommended for batch jobs, Big Data analysis, or workloads that are resilient to failures.
• Not recommended for critical jobs or databases.

Dedicated Hosts

• Physical server with EC2 instance capacity fully dedicated to your use
• Visibility and control over how instances are placed on the server
• More expensive
• Useful for software that have a complicated licensing model (BYOL)
• Useful for companies that have strong regulatory or compliance needs.

Dedicated Instances

• Pay, by the hour, for instances that run on single-tenant hardware.
• Instances running on hardware that’s dedicated to you
• May share hardware with other instances in same account
• No control over instance placement (can move hardware after stop/start)