7.2. Sealing Virtual Machines in Preparation for Deployment as Templates

This section describes procedures for sealing Linux and Windows virtual machines. Sealing is the process of removing all system-specific details from a virtual machine before creating a template based on that virtual machine. Sealing is necessary to prevent the same details from appearing on multiple virtual machines created based on the same template. It is also necessary to ensure the functionality of other features, such as predictable vNIC order.

7.2.1. Sealing a Linux Virtual Machine for Deployment as a Template

To seal a Linux virtual machine during the template creation process, select the Seal Template check box in the New Template window. See Creating a template from an existing virtual machine for details.


In RHV 4.4, to seal a RHEL 8 virtual machine for a template, its cluster level must be 4.4 and all hosts in the cluster must be based on RHEL 8. You cannot seal a RHEL 8 virtual machine if you have set its cluster level to 4.3 so it can run on RHEL 7 hosts.

7.2.2. Sealing a Windows Virtual Machine for Deployment as a Template

A template created for Windows virtual machines must be generalized (sealed) before being used to deploy virtual machines. This ensures that machine-specific settings are not reproduced in the template.

Sysprep is used to seal Windows templates before use. Sysprep generates a complete unattended installation answer file. Default values for several Windows operating systems are available in the /usr/share/ovirt-engine/conf/sysprep/ directory. These files act as templates for Sysprep. The fields in these files can be copied, pasted, and altered as required. This definition will override any values entered into the Initial Run fields of the Edit Virtual Machine window.

The Sysprep file can be edited to affect various aspects of the Windows virtual machines created from the template that the Sysprep file is attached to. These include the provisioning of Windows, setting up the required domain membership, configuring the hostname, and setting the security policy.

Replacement strings can be used to substitute values provided in the default files in the /usr/share/ovirt-engine/conf/sysprep/ directory. For example, "<Domain><![CDATA[$JoinDomain$"]></Domain>" can be used to indicate the domain to join. Prerequisites for Sealing a Windows Virtual Machine


Do not reboot the virtual machine while Sysprep is running.

Before starting Sysprep, verify that the following settings are configured:

  • The Windows virtual machine parameters have been correctly defined.
  • If not, click Edit in ComputeVirtual Machines and enter the required information in the Operating System and Cluster fields.
  • The correct product key has been defined in an override file on the Manager.

The override file must be created under /etc/ovirt-engine/osinfo.conf.d/, have a filename that puts it after /etc/ovirt-engine/osinfo.conf.d/00-defaults.properties, and ends in .properties. For example, /etc/ovirt-engine/osinfo.conf.d/10-productkeys.properties. The last file will have precedence and override any other previous file.

If not, copy the default values for your Windows operating system from /etc/ovirt-engine/osinfo.conf.d/00-defaults.properties into the override file, and input your values in the productKey.value and sysprepPath.value fields.

Example 7.1. Windows 7 Default Configuration Values

# Windows7(11, OsType.Windows, false),false
os.windows_7.id.value = 11
os.windows_7.name.value = Windows 7
os.windows_7.derivedFrom.value = windows_xp
os.windows_7.sysprepPath.value = ${ENGINE_USR}/conf/sysprep/sysprep.w7
os.windows_7.productKey.value =
os.windows_7.devices.audio.value = ich6
os.windows_7.devices.diskInterfaces.value.3.3 = IDE, VirtIO_SCSI, VirtIO
os.windows_7.devices.diskInterfaces.value.3.4 = IDE, VirtIO_SCSI, VirtIO
os.windows_7.devices.diskInterfaces.value.3.5 = IDE, VirtIO_SCSI, VirtIO
os.windows_7.isTimezoneTypeInteger.value = false Sealing a Windows 7, Windows 2008, or Windows 2012 Virtual Machine for Deployment as Template

Seal a Windows 7, Windows 2008, or Windows 2012 virtual machine before creating a template to use to deploy virtual machines.


  1. On the Windows virtual machine, launch Sysprep from C:\Windows\System32\sysprep\sysprep.exe.
  2. Enter the following information into Sysprep:

    • Under System Cleanup Action, select Enter System Out-of-Box-Experience (OOBE).
    • Select the Generalize check box if you need to change the computer’s system identification number (SID).
    • Under Shutdown Options, select Shutdown.
  3. Click OK to complete the sealing process; the virtual machine shuts down automatically upon completion.

The Windows 7, Windows 2008, or Windows 2012 virtual machine is sealed and ready to create a template to use for deploying virtual machines.