Creating VMs

A virtual machine (VM) is a software container that runs on a host physical computer. The VM behaves as if it were a physical computer itself. VMs consist of an operating system plus CPU, memory (RAM) and networking resources, and software applications.

A template is a virtual machine encapsulated into a file, making it possible to rapidly deploy new VMs. Each template contains installation metadata—the setup information needed to create a VM with a specific guest operating system, and with the optimum storage, CPU, memory, and virtual network configuration.

You can create VMs in XenCenter in several different ways:

  • The New VM wizard takes you step by step through the process of creating a VM from a template or a snapshot, allowing you to configure operating system, CPU, storage, networking, and other parameters.
  • You can bypass the New VM wizard and create an instant VM based on a custom VM template that specifies all required VM configuration parameters. You simply select your preconfigured template in XenCenter then right-click and select Instant VM from template. This mode of unattended VM installation can be useful for deploying large numbers of identical VMs.
  • You can copy (or “clone”) an existing VM.
  • You can import a VM that has been previously exported.

Citrix VM Tools

VMs in Citrix Hypervisor environment might be fully virtualized (HVM) or paravirtualized:

  • In HVM (hardware-assisted virtualization or Hardware Virtual Machine) mode, the VM is fully virtualized and can run at near-native processor speeds on virtualization-enabled hardware, without any modification to the guest operating system.

    HVM Linux VMs can take advantage of the x86 virtual container technologies in newer processors for improved performance. Network and Storage access from these VMs still operate in PV mode, using the drivers built into the kernels. For information about upgrading your existing Linux VMs to versions which now operate in HVM mode, see the Update Linux Kernels and Guest Utilities section in Linux VMs.

  • In paravirtualized (non-HVM) mode, the guest operating system is tuned and optimized to run in a virtual environment, independent of the underlying processor capabilities. The result is better performance and greater flexibility.

    For detailed information about supported guest operating systems, see Guest operating system support.

I/O drivers (also known as Paravirtualized drivers or PV drivers) are available for Windows and Linux VMs to enhance disk and network performance. Install these drivers on all new VMs. In all supported versions of Citrix Hypervisor and XenServer, the I/O drivers can be installed and updated through the Windows Update mechanism. The I/O drivers and the Management Agent are combined and issued as Citrix VM Tools for ease of installation. For more information, see Installing Citrix VM Tools. Citrix Hypervisor features such as VM migration and historical performance data tracking are only available on VMs that have Citrix VM Tools installed.

Using templates

Several different templates are supplied with Citrix Hypervisor. These templates contain all the various configuration settings needed to install a specific guest operating system on a new VM. You can also create your own customized templates configured with the appropriate guest operating system, memory, CPU, storage and network settings, and use them to create VMs. See Guest OS support for a list of the templates/operating systems supported at this release, and for detailed information about the different install mechanisms on Windows and Linux.

You can view the Citrix Hypervisor templates supplied with the product and any custom templates that you create in the Resources pane.

  • Citrix Hypervisor template icon Citrix Hypervisor template
  • Custom template icon Custom template

You can control whether to display the Citrix Hypervisor and Custom templates in the Resources pane:

  • In the XenCenter Navigation pane, select Infrastructure.

    This panel displays a tree view of your managed resources in the Resources pane.

  • To display standard Citrix Hypervisor VM templates: on the View menu, select Citrix Hypervisor Templates. To hide Citrix Hypervisor templates, select again to remove the check mark.
  • To show custom VM templates: on the View menu, select Custom Templates. To hide custom templates, select again to remove the check mark.

Creating VMs