A placement group is a logical grouping of instances within a single availability zone that enables applications to participate in a faster network, up to 25 Gbps, depending on the instance type.
You must create a placement group before deploying Teradata Database. Using placement groups for Teradata Data Mover, Teradata Server Management, and Teradata DSC instances can improve performance.
After creating a placement group, you can deploy multiple instances into the same group. For example, create a placement group containing the Teradata Database and Teradata DSC instances. When deploying a Teradata ecosystem, you can launch Teradata Database, Teradata Data Mover, and Teradata DSC in the same placement group. Use placement groups for these products, especially if you plan to move large amounts of data.
Teradata recommends using the same instance types within a placement group, as mixing instance types may result in AWS insufficient capacity errors. After deploying an instance, you should not modify the placement group.