Chapter 6.8 - Optimizing with EC2 Placement Groups

Question 1

What are Placement Groups?

Answer 1

A Placement Group is a methodology that allows you to influence the placement of a group of interdependent instances to meet the needs of your workload while minimizing correlated failures by placing instances in such a way that all of your instances are spread out across underlying hardware.

Question 2

What are the 3 Types of Placement Groups and their basic use cases?

Answer 2

Cluster Placement Groups
Low network latency, high network throughput

Partition Placement Groups
Multiple EC2 instances; HDFS, HBase, and Cassandra

Spread Placement Groups
Individual critical EC2 instances

Question 3

What are the fundamental characteristics of Cluster Placement Groups?

Answer 3

Grouping of instances within a single placement Availability Zone.

Recommended for applications that need low network latency, high network throughput, or both.

Only certain instance types can be launched into a cluster placement group.

Question 4

What are the fundamental characteristics of Partition Placement Groups?

Answer 4

Each partition placement group has it’s own set of racks.

Each rack has its own network and power source.

No two partitions within a placement group share the same racks, allowing you to isolate the impact of hardware failure within your application.

Used for multiple instances and you want them to be on their own dedicated network and power sources.

Question 5

What are the fundamental characteristics of Spread Placement Groups?

Answer 5

A spread placement group is a group of instances that are each placed on distinct underlying hardware.

Spread placement groups are recommended for applications that have a small number of critical instances that should be kept separate from each other.

Used for individual instances such as a primary database and a backup database.

Question 6

Which Placement Group types can and cannot span multiple Availability Zones?

Answer 6

Cluster = No

Partition and Spread = Yes

Question 7

What types of instances CAN be launched into a Placement Group?

Answer 7

Compute optimized

GPU optimized

Memory optimized

Storage optimized

Question 8

How is merging and moving of Placement Groups handled?

Answer 8

You can’t merge placement groups.

You can move an existing instance into a placement group. Before you move the instance, the instance must be in a stopped state. You can move or remove an instance using the AWS CLI or an AWS SDK, but you can’t do it via the console yet.