# Host Aggregate

A host aggregate is a **group of hosts** within your virtualized cluster that share common characteristics. Host aggregates are a mechanism to create specialized groupings of hosts that have specific properties, with the purpose of enabling provisioning of VMs that require those properties on those hosts.

You can create a host aggregate by navigating to the <code class="expression">space.vars.product\_name</code> UI and selecting 'Infrastructure' -> 'Host Aggregates' from the left nav bar. When you create a new host aggregate, you get to specify a name for the aggregate and a set of key-value pairs that describe the specific properties of the hosts that will belong to this host aggregate.

For example, you may wish to create a group of hosts within your virtualized cluster that have Oracle licensing enabled on them. You can do this by creating an aggregate called "Oracle Hosts" and within that aggregate, creating a key-value pair with values "Oracle-License" and "True". You can then add the hosts that you know have Oracle license installed on them to this aggregate.

This will enable you to provision VMs that require Oracle licensing to place on these hosts. You will do this by first creating a flavor that references this host aggregate and then using that flavor to create your VM. Read about [Flavors and Host Aggregates](https://docs.platform9.com/private-cloud-director/virtualmachine#flavors-and-host-aggregates) for how to do this.


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