A placement group is a logical grouping of instances.
You first create a cluster placement group, then launch multiple cluster compute instances into
the group. Currently cluster compute instances are available only in the US-East (Northern
Virginia) Region. You must give each placement group a name that is unique within your account.
For more information about cluster placement groups, see Cluster Compute Instance Concepts.
Note
You can't merge cluster placement groups. Instead you must terminate the instances in one of the
groups, and then relaunch the instances into the other group.