# Add a template-based RD Session Host

A template-based RD Session Host is a clone of a virtual machine running on a hypervisor or a cloud-based provider. When you create a template, you select a preconfigured VM with the operating system and applications already installed. Individual hosts (VMs) are then created as clones of the template. The clones can be created in advance or on as-needed basis (configurable when you create a template). This functionality allows you to create and configure an RD Session Host running in a virtual machine and then create as many copies of it as you require.

To add a template-based RD Session Host to a Site:

1. Create a template as described in [**Creating an RD Session Host template**](/landing/ras-admin-guide/parallels-ras-21-administrators-guide/rd-session-hosts/manage-rd-session-hosts/manage-templates-rd-session-hosts/creating-an-rd-session-host-template.md).
2. Assign the template to a host pool as described in [**Assigning a template to a host pool**](/landing/ras-admin-guide/parallels-ras-21-administrators-guide/rd-session-hosts/manage-rd-session-hosts/manage-templates-rd-session-hosts/assigning-a-template-to-a-host-pool-rd-session-host.md).
3. Add individual RD Session Hosts to the host pool. Do one of the following:
   * If you want to add RD Session Hosts manually, go to the host pool properties, select the **Servers** tab and click **Tasks > Add** (or click the **\[+]** icon). In the dialog that opens, select the number of RD Session Host you want to create and click **OK**.
   * If you want Parallels RAS to add RD Session Hosts automatically when certain conditions are met, configure autoscaling as described in [**Manage host pools (RD Session Hosts)**](/landing/ras-admin-guide/parallels-ras-21-administrators-guide/rd-session-hosts/manage-rd-session-hosts/manage-host-pools-rd-session-hosts.md)[.](https://download.parallels.com/ras/v19/docs/en_US/Parallels-RAS-19-Administrators-Guide/39316.htm)


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