[Getting Started] Getting Started with Amazon EC2 Reserved Instances

Nice to meet you.
I'm Infrastructure Wasshoiman from the System Solutions Department.

Since joining Beyond in September, I have been involved in a variety of tasks and my days are fulfilling

Well, this time we'll be talking about AWS instances, "Amazon EC2."

Introduction

I'd like to briefly talk about the costs that you will inevitably consider when using AWS EC2 instances

When creating an EC2 instance, to use an on-demand instance, which is a pay-as-you-go model

However, when I was researching the pricing structure for AWS instances, I came across the following sentence:

Amazon EC2 Reserved Instances (RIs) allow you to reserve capacity for use in a specific Availability Zone at a significant discount (up to 72%) compared to On-Demand pricing

Source: AWS https://aws.amazon.com/jp/ec2/pricing/reserved-instances/

Up to 72% off!? Seriously!?

The Reserved Instance
offered by AWS is a very advantageous system as described above if the conditions are met

However, it is a hassle to read and understand the documentation, and even after reading it, you may end up not understanding it very well. (That's what happened to me at first.)

Reserved instances can be a little difficult to understand, but I happened to have the opportunity to come into contact with them at work, so I thought I would summarize what they are, assuming they are for beginners who, like me, have never used them before

Please note that although Reserved Instances can also be used with other services such as Amazon RDS, this article is an introductory guide and will focus on EC2 Reserved Instances

What are Reserved Instances?

First, what is a Reserved Instance? Simply put, it a commuter pass for an instance .

In short, if you buy a year's (or three years') supply at once, we'll give you a discount!

Please note that this is a good deal if you keep your instance running all the time, but it would be a waste to apply it if you stop your instance frequently

It seems like a waste to buy a train pass if you only take it occasionally, right?

So, before you start using it, make sure you understand how you will operate the instance!

There are also many features that you should be aware of when using it, so we will list some of the most notable points below

Classes offered

There are two types of Reserved Instances available, and you can choose the one that best suits your situation

Standard

• Super cheap (up to 72% off compared to on-demand)
• You cannot change the instance type mid-stream
• Can be sold on the marketplace

Convertible

• More expensive than standard (up to 54% off compared to on-demand)
• You can change to an instance type that is more expensive than the type you purchased
• Can't sell on the marketplace

Considering the load and usage scenarios related to the service, if you don't expect to change the instance type you use, it is more cost-effective to choose Standard! (It also gives you peace of mind knowing that even if you make a mistake, you can still sell it.)

How to purchase and apply

When purchasing a Reserved Instance, you will need to decide on the following items, so be sure to decide them before purchasing

• Platform (Linux/Unix, Windows, Red Hat Enterprise Linux, etc.)
• Region or Availability Zone
• Tenancy (how you rent the server. Default means you share it with others, dedicated means you have it all to yourself)
• Instance type (t2.micro, m4.large, etc.)
• Contract period (1 year or 3 years)
• Payment method (Choose from full upfront payment, partial upfront payment, or no upfront payment. For all other options, you pay the remaining amount monthly.)

Also, please note that there is a quirk in the way instances are applied.
Reserved Instances are not purchased tied to a specific instance, but are automatically applied if an instance that matches the conditions is available after purchase

For example, if you purchase a Reserved Instance with an m4.large instance, Windows OS, default tenancy, and Availability Zone ap-northeast-3, it will be automatically applied to any EC2 instance that matches all the conditions

*However, please note that if you purchase an instance, you will be charged even if there is no instance that matches the conditions or the instance is not running. Also, please note that the offer will not apply if the region is different

summary

This article only covers the very basics, but I hope you were able to get a general idea of ​​what Reserved Instances are

There isn't much to think about and it's not difficult to buy

This is a very cost-effective system for running the same instance over the long term, so don't hesitate to take advantage of it and reduce costs!