# Server Groups Server groups can be used to control the affinity and anti-affinity scheduling policy for a group of servers. An affinity policy for a server group denotes that all the virtual machine instances belonging to the server group would be hosted on a single hypervisor host. An anti-affinity policy for a server group denotes that each virtual machine instance belonging to the server group would be hosted on a different hypervisor host. An anti-affinity policy facilitates fault tolerance through redundancy, and helps in disaster recovery. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.platform9.com/managed-openstack/5.8/instances/virtual-machines-server-groups.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.