Anti-Affinity groups let you specify which instances should run on separate hosts. In case of a HA cluster for example you may wish to keep your instances on separate hypervisors to ensure a more reliable fault tolerance.
How it works
Create an Anti-Affinity group through the console. Now whenever you create a new instance you may assign it to a group. Instances in a given anti-affinity group are all spawned on different hypervisors.
