OS templates in VMmanager

VMmanager utilizes OS templates to install operating systems (OS) on virtual machines. OS templates in VMmanager are images of the virtual machine disks with an operating system without additional software applications and special settings ("clean" OS). The installation of an operating system on a virtual machine includes two steps: 

  1. Recovery of VM disk from the image of the selected operating system.
  2. Automatic configuration of network parameters. 

Images are kept in .xz archives with maximum compression and are uploaded to a cluster node only after the first deployment of the operating system on a virtual machine.  

Images are sparse files — the sequence of null bytes in them is replaced by information about these sequences. This saves disk space on the cluster node.

The following operating systems can be installed from the ISPsystem repository on a virtual machine: 

OS groupSupported OS
  • AlmaLinux 8
  • CentOS 7
  • CentOS 8
  • CentOS 8 Stream
  • CentOS 9 Stream
  • Debian 9
  • Debian 10
  • Debian 11
  • Debian 12
  • FreeBSD 12
  • FreeBSD 13 

    The FreeBSD 13 template deploys an OS image with the UFS, the FreeBSD 13 ZFS template deploys an OS image with the ZFS.

  • Oracle Linux 8
  • Rocky Linux 8
  • Ubuntu 16.04
  • Ubuntu 18.04
  • Ubuntu 20.04
  • Ubuntu 22.04
  • VzLinux 8
  • Windows 10
  • Windows 11
  • Windows Server 2012 R2
  • Windows Server 2016
  • Windows Server 2019
  • Windows Server 2022


Some functions may not be supported on Windows virtual machines. Learn more in Specifics of VM running on Windows

OS information is displayed in Templates → Operating systems. For more detailed information, click on the OS name. Learn more about the OS parameters in the article Editing an OS template


To activate Windows, specify the license key or your own KMS server settings in the template parameters. Read more in Editing an OS template.

KMS server (Key Management Service) allows you to activate corporate versions of Windows within your network without connecting to a Microsoft server. You can use a physical or virtual Windows server as KMS. A corporate Windows license and a KMS key are required for installation. Read more in the official Microsoft documentation. You can configure VM access to the KMS server via template settings or via SRV records on your DNS server.

A copy of Windows will be activated when the template is installed on the VM. If no licensing settings are specified in the template parameters, a trial version of Windows will be installed on the VM.

To check activation of the OS, run the following command on the VM:

slmgr.vbs /dli

Compatibility with scripts

Scripts allow configuring virtual machines automatically: install software programs, modify configuration files, etc. Normally, every script is developed for a certain operating system. E.g. a script for CentOS 7 may work incorrectly on Debian 9, as the configuration files of the system are located in different repositories.  VMmanager uses tags to define that scripts are compatible with a certain operating system. A script can be executed on an operating system provided that they have at least one similar tag.  The OS tags cannot be changed that's why you need to specify the tags when creating a new script. Learn more in the article Creating a script for the VM