Anti-Affinity Groups
From COMPUTE in the Portal, select the ANTI-AFFINITY section. You can then create, delete, or view the details of your groups, and in the detail of a group, you can see the instances attributed to that group.
Associating Anti-Affinity Groups
When you create an instance, you will see a list of your Anti-Affinity Groups. You can choose to associate your instance with any number of groups. Please note that you will have this option only during the instance creation. Although there is no limit to the number of groups you may have, an Anti-Affinity Group cannot contain more than 8 instances. If a group is full, it will not be presented in the available options.