Elastic Compute Cloud (EC2)

Icon

EC2 Icon

Basics

• Introduction

User Data

• User Data is basically bootstrap script that runs once at the instance's first start of its entire lifecycle.

• This enables us to run software installation, updates.

• This script runs with root privilege.

Instance Types

• They are categorized based on instance types.

• Detailed list can be found here.
• For comparison of instance type visit this.

Naming convention

• <instance-class><class-generation>.<size-of-instance-class>

• Example: m5.2xlarge

  m: instance class
  5: generation class
  2xlarge: size within instance class

Instances Puchasing Options

• The following are different purchasing options available for EC2 instance.

On-Demand Instances

• Pay as per your usage

  • Windows and Linux, billing per second, after first minute.

  • Other OS, billing per hour.

• Highest cost but no upfront payment.

• No long-term commitment.

• Recommended for short and uninterrupted workloads, where you can't predict application behavior.

Reserved (1 or 3 years)

Reserved Instances

• Upto 72% discount (aws may change this over time) compared to On-demand.

• Reserve based on specific instance attribute (Instance Type, Region, Tenancy, OS).

• Payment Options - No/partial/fully upfront, where all upfront gives maximum discount.

• Scope can be regional or zonal.

• Recommended for steady-state usage applications.

• Can buy or sell reserved instances from Reserved Instance Marketplace.

Convertible Reserved Instances

• Can changes EC2 insance type, family, OS, scope and tenancy.

• Upto 66% discount (aws may change this over time).

Savings Plan (1 & 3 years)

• Discount based on long term usage (upto 72% same as Reserved instances) (aws may change this over time).

• Requires commitment to certain type of usage (like Rs1000 per hour).

• Usage beyond the savings plan is billed on On-Demand instance family.

• Locked to a specific instance family and region. However instance-size, OS, tenancy can be changed.

Spot Instances

• Can get upto 90% discount compared to On Demand.

• These are instances which you can lose at any point in time if max price is less than the current spot price.

• This is the most cost-efficient instances in AWS.

• Recommended for work-load that is resillient to failure like batch jobs, data analysis, image processing, workloads with flexible start and end time.

• Not suitable for critical jobs or databases.

Dedicated Instances

• Instances run on hardware that's dedicated to you.

• May share hardware with other instances in same account, but not with other account.

• No control over instance placement.

Dedicated Hosts

• A physical server with EC2 instance capacity fully dedicated to your use, will not be shared with any other customer (dedicates a physical server).

• Can control instance placement.

• Recommended to address strong regulatory or compliance requirement.

• Purchasing options can be like on-demand and reserved (1 year or 3 year). Most expensive option.

• Useful for softwares that have complicated licensing model (BYOL - Bring Your Own License).

• Gives you visibility to the underlying hardware unlike Dedicated Instances.

Capacity Reservations

• Reserve On-demand instances capacity in a specific AZ for any duration.

• You always have EC2 capacity when you need it.

• No time commitment, no billing discounts.

• To get discounts one can combine them with Regional Reserved Instances and Savings Plan.

• Charged based on On-demand rate whether you run instances or not.

• Suitable for short-term, uninterrupted workloads in a specific AZ.

References

• Read more about EC2 instance pricing here.
• Read more about EC2 instance life-cycle here.
• Difference between Dedicated Host v/s Dedicated Instance