text: Figure 5-5 PowerVC dualHost Groups (Availability Zones) 
  
  **Colocation rules**
  Colocation rules, also known as*server groups*in OpenStack’s terminology, are used to 
  specify that selected virtual machines must always be kept on the same host (affinity) or can 
  never be placed on the same host (anti-affinity). 
  
  During deployment, migration, and remote restart, PowerVC ensures that these colocation 
  rules are followed. 