> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xloud.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Compute Scheduling

> Configure host aggregates and availability zones in Xloud Compute to control how instances are placed across the cluster.

## Overview

The Xloud Compute scheduler determines which physical host runs each new instance.
Administrators configure the scheduler behavior through host aggregates (logical
groupings of hosts with shared properties) and availability zones (fault domains).
The Dashboard provides management interfaces for both.

<Warning>
  **Administrator Access Required** — This operation requires the `admin` role. Contact your
  Xloud administrator if you do not have sufficient permissions.
</Warning>

<Note>
  **Prerequisites**

  * Administrator access to the Xloud Dashboard (admin view)
</Note>

***

## Host Aggregates

Host aggregates group compute hosts with shared characteristics (e.g., SSD storage,
GPU hardware, high-memory nodes). The scheduler uses aggregate metadata to match
instances with compatible hosts.

<Tabs>
  <Tab title="Dashboard" icon="gauge">
    Navigate to **Compute > Host Aggregates** in the admin sidebar. The **Host Aggregate**
    tab shows:

    | Column                | Description                             |
    | --------------------- | --------------------------------------- |
    | **Name**              | Aggregate name                          |
    | **Availability Zone** | Zone associated with this aggregate     |
    | **Hosts**             | List of compute hosts in the aggregate  |
    | **Metadata**          | Key-value properties (e.g., `ssd=true`) |
    | **Created At**        | Creation timestamp                      |

    **Available actions**:

    | Action              | Location         | Description                                    |
    | ------------------- | ---------------- | ---------------------------------------------- |
    | **Edit**            | First row action | Change name and availability zone              |
    | **Manage Host**     | More dropdown    | Add or remove compute hosts from the aggregate |
    | **Manage Metadata** | More dropdown    | Set key-value metadata properties              |
    | **Delete**          | More dropdown    | Delete the aggregate                           |
  </Tab>

  <Tab title="CLI" icon="terminal">
    ```bash title="Source credentials" theme={null}
    source openrc.sh
    ```

    <CodeGroup>
      ```bash title="List host aggregates" theme={null}
      openstack aggregate list
      ```

      ```bash title="Show aggregate details" theme={null}
      openstack aggregate show <AGGREGATE_NAME>
      ```
    </CodeGroup>
  </Tab>
</Tabs>

***

## Create a Host Aggregate

<Tabs>
  <Tab title="Dashboard" icon="gauge">
    <Steps titleSize="h3">
      <Step title="Open the Create Aggregate dialog">
        Navigate to **Compute > Host Aggregates**. Click **Create Host Aggregate**.
      </Step>

      <Step title="Configure the aggregate">
        | Field                            | Type           | Required                     | Description                                |
        | -------------------------------- | -------------- | ---------------------------- | ------------------------------------------ |
        | **Name**                         | Text           | Yes                          | Aggregate name                             |
        | **Create New Availability Zone** | Radio (Yes/No) | Yes                          | Whether to create a new AZ or use existing |
        | **Availability Zone**            | Dropdown       | Required if not creating new | Select existing zone                       |
        | **New Availability Zone**        | Text           | Required if creating new     | Name for the new zone                      |

        Click **Confirm**.
      </Step>
    </Steps>
  </Tab>

  <Tab title="CLI" icon="terminal">
    <CodeGroup>
      ```bash title="Create aggregate with existing zone" theme={null}
      openstack aggregate create --zone <ZONE_NAME> <AGGREGATE_NAME>
      ```

      ```bash title="Create aggregate with new zone" theme={null}
      openstack aggregate create --zone new-zone <AGGREGATE_NAME>
      ```

      ```bash title="Add hosts to aggregate" theme={null}
      openstack aggregate add host <AGGREGATE_NAME> <HOSTNAME>
      ```

      ```bash title="Set metadata" theme={null}
      openstack aggregate set --property ssd=true <AGGREGATE_NAME>
      ```
    </CodeGroup>
  </Tab>
</Tabs>

***

## Manage Hosts in an Aggregate

<Tabs>
  <Tab title="Dashboard" icon="gauge">
    Click the **More** dropdown on an aggregate row and select **Manage Host**.

    The dialog shows a multi-select table of all compute hosts (service: `nova-compute`).
    Currently assigned hosts are pre-selected. Toggle hosts to add or remove them.

    The table shows: Host, Availability Zone, Admin Status, State, Last Updated.
  </Tab>

  <Tab title="CLI" icon="terminal">
    <CodeGroup>
      ```bash title="Add host to aggregate" theme={null}
      openstack aggregate add host <AGGREGATE_NAME> <HOSTNAME>
      ```

      ```bash title="Remove host from aggregate" theme={null}
      openstack aggregate remove host <AGGREGATE_NAME> <HOSTNAME>
      ```
    </CodeGroup>
  </Tab>
</Tabs>

***

## Availability Zones

The **Availability Zones** tab on the Host Aggregates page shows a read-only list
of all configured zones. Zones are created through host aggregates — each aggregate
can be associated with one availability zone.

<Note>
  Availability zones are a subset of host aggregates. Create an aggregate with a
  zone name to define a new availability zone. See
  [Availability Zones](/services/compute/availability-zones) for user-facing
  documentation on zone selection during instance launch.
</Note>

***

## Next Steps

<CardGroup cols={2}>
  <Card title="Compute Hosts" href="/services/compute/compute-hosts" color="#197560">
    Monitor hypervisor resource utilization
  </Card>

  <Card title="Availability Zones" href="/services/compute/availability-zones" color="#197560">
    Understand fault domains and zone placement
  </Card>

  <Card title="Live Migration" href="/services/compute/live-migration" color="#197560">
    Move instances between hosts for maintenance
  </Card>

  <Card title="Flavors" href="/services/compute/flavors" color="#197560">
    Create flavors with aggregate-matching extra specs
  </Card>
</CardGroup>