Using Placement Groups is optional and not required. If using a placement group, Ribbon recommends using a cluster placement group so that all resources are within the same AZ to maximize performance.
Create a placement group in advance, or during Instance instantiation.
To create a placement group, perform the following procedure:
Navigate to the EC2 Management Console.
Select NETWORK & SECURITY > Placement Groups.
The Placement Groups page displays.
The following figure depicts the Create Placement Group page.