1. Overview

An EC2 Placement Group is a logical grouping of EC2 instances within an AWS Region.

It influences how AWS places your instances on the underlying hardware to optimize network performance, fault tolerance, or scalability depending on the chosen placement strategy.

2. Purpose of Placement Groups

By default, AWS places your instances randomly across hardware to minimize correlated failures.

Placement groups allow you to control the placement to achieve one of these goals:

• Low-latency networking for tightly coupled applications
• High availability
• Scalable distributed systems

3. Types of Placement Groups

AWS supports three main types of placement groups:

A. Cluster Placement Group

• Places instances close together in a single Availability Zone.
• Designed for high network throughput and low latency between instances.
• Ideal for:
  • High-performance computing (HPC)
  • Big data analytics
  • Real-time processing

Key Points:

• All instances must be in the same Availability Zone.