# Launch Amazon EC2 instances on an Amazon EC2 Dedicated Host After you have allocated a Dedicated Host, you can launch instances onto it. You can't launch instances with `host` tenancy if you do not have active Dedicated Hosts with enough available capacity for the instance type that you are launching. **Considerations** + SQL Server, SUSE, and RHEL AMIs provided by Amazon EC2 can't be used with Dedicated Hosts. + For Dedicated Hosts that support multiple instance sizes, we recommend that you launch the larger instance sizes first, and then fill the remaining instance capacity with the smaller instance sizes as needed. + Before you launch your instances, take note of the limitations. For more information, see [Dedicated Hosts restrictions](dedicated-hosts-overview.md#dedicated-hosts-limitations). ------ #### [ Console ] **To launch an instance onto a specific Dedicated Host from the Dedicated Hosts page** 1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/). 1. Choose **Dedicated Hosts** in the navigation pane. 1. On the **Dedicated Hosts** page, select a host and choose **Actions**, **Launch Instance(s) onto host**. 1. In the **Application and OS Images** section, select an AMI from the list. 1. In the **Instance type** section, select the instance type to launch. **Note** If the Dedicated Host supports a single instance type only, the supported instance type is selected by default and can't be changed. If the Dedicated Host supports multiple instance types, you must select an instance type within the supported instance family based on the available instance capacity of the Dedicated Host. We recommend that you launch the larger instance sizes first, and then fill the remaining instance capacity with the smaller instance sizes as needed. 1. In the **Key pair** section, select the key pair to associate with the instance. 1. In the **Advanced details** section, for **Tenancy affinity**, choose one of the following: + **Off** — Host affinity disabled. The instance launches onto the specified host, but it is not guaranteed to restart on the same Dedicated Host if stopped. + A Dedicated Host ID — Host affinity enabled. If stopped, the instance always restarts on this specified host if it has capacity. If the host does not have capacity, the instance can't be restarted; you must establish affinity with a different host. For more information about Affinity, see [Amazon EC2 Dedicated Host auto-placement and host affinity](dedicated-hosts-understanding.md). **Note** The **Tenancy** and **Host** options are pre-configured based on the host that you selected. 1. Configure the remaining instance options as needed. For more information, see [Reference for Amazon EC2 instance configuration parameters](ec2-instance-launch-parameters.md). 1. Choose **Launch instance**. **To launch an instance onto a Dedicated Host using the Launch Instance wizard** 1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/). 1. In the navigation pane, choose **Instances**, **Launch instance**. 1. In the **Application and OS Images** section, select an AMI from the list. 1. In the **Instance type** section, select the instance type to launch. 1. In the **Key pair** section, select the key pair to associate with the instance. 1. In the **Advanced details** section, do the following: 1. For **Tenancy**, select **Dedicated Host**. 1. For **Target host by**, select **Host ID**. 1. For **Target host ID**, select the host onto which to launch the instance. 1. For **Tenancy affinity**, choose one of the following: + **Off** — Host affinity disabled. The instance launches onto the specified host, but it is not guaranteed to restart on the same Dedicated Host if stopped. + A Dedicated Host ID — Host affinity enabled. If stopped, the instance always restarts on this specified host if it has capacity. If the host does not have capacity, the instance can't be restarted; you must establish affinity with a different host. For more information about Affinity, see [Amazon EC2 Dedicated Host auto-placement and host affinity](dedicated-hosts-understanding.md). 1. Configure the remaining instance options as needed. For more information, see [Reference for Amazon EC2 instance configuration parameters](ec2-instance-launch-parameters.md). 1. Choose **Launch instance**. ------ #### [ AWS CLI ] **To launch an instance onto a Dedicated Host** Use the [run-instances](https://docs.aws.amazon.com/cli/latest/reference/ec2/run-instances.html) command and specify the instance affinity, tenancy, and host in the `--placement` option. To launch onto a specific Dedicated Host with host affinity (instance always restarts on the same host if stopped): ``` --placement Affinity=host,Tenancy=host,HostId=h-07879acf49EXAMPLE ``` To launch onto a specific Dedicated Host without host affinity (instance can restart on any available host): ``` --placement Tenancy=host,HostId=h-07879acf49EXAMPLE ``` To launch onto any available Dedicated Host with auto-placement enabled and matching instance type: ``` --placement Tenancy=host ``` ------ #### [ PowerShell ] **To launch an instance onto a Dedicated Host** Use the [New-EC2Instance](https://docs.aws.amazon.com/powershell/latest/reference/items/New-EC2Instance.html) cmdlet and specify the instance affinity, tenancy, and host in the `-Placement` parameter. To launch onto a specific Dedicated Host with host affinity (instance always restarts on the same host if stopped): ``` -Placement_Affinity host ` -Placement_Tenancy host ` -Placement_HostId h-07879acf49EXAMPLE ``` To launch onto a specific Dedicated Host without host affinity (instance can restart on any available host): ``` -Placement_Tenancy host ` -Placement_HostId h-07879acf49EXAMPLE ``` To launch onto any available Dedicated Host with auto-placement enabled and matching instance type: ``` -Placement_Tenancy host ``` ------