Host aggregates enable administrative users to assign key-value pairs to groups of machines. Each node can have multiple aggregates and each aggregate can have multiple key-value pairs. You can assign the same key-value pair to multiple aggregates. The scheduler uses this information to make scheduling decisions. For information, see Scheduling. Log in to the dashboard. Choose the admin project from the drop-down list at the top of the page. On the Admin tab, open the System Panel and click the Host Aggregates category. Click Create Host Aggregate. In the Create Host Aggregate dialog box, enter or select the following values on the Host Aggregate Info tab: Name: The host aggregate name. Availability Zone: The cloud provider defines the default availability zone, such as us-west, apac-south, or nova. You can target the host aggregate, as follows: When the host aggregate is exposed as an availability zone, select the availability zone when you launch an instance. When the host aggregate is not exposed as an availability zone, select a flavor and its extra specs to target the host aggregate. Assign hosts to the aggregate on the Host within Aggregate tab. To assign a host to the aggregate, click + for the host. The host moves from the All available hosts list to the Selected hosts list. You can add one host to one or more aggregates. To add a host to an existing aggregate, edit the aggregate. Choose the admin project from the drop-down list at the top of the page. On the Admin tab, open the System Panel and click the Host Aggregates category. To edit host aggregates, select the host aggregate that you want to edit. Click Edit Host Aggregate. In the Edit Host Aggregate dialog box, you can change the name and availability zone for the aggregate. To manage hosts, locate the host aggregate that you want to edit in the table. Click More and select Manage Hosts. In the Add/Remove Hosts to Aggregate dialog box, click + to assign a host to the aggregate. Click - to remove a host that is assigned to an aggregate. To delete host aggregates, locate the host aggregate that you want to edit in the table. Click More and select Delete Host Aggregate.