Creating Virtual Machines in DaDesktop via Virt Manager

Introduction

When preparing course materials, it is often beneficial to virtualise a server within DaDesktop. In many cases, you may also want to virtualise one or two client machines using the same method, whether running the same operating system or a combination of Windows and Linux.

Running 'Nested VMs' can be achieved using either Virt Manager or VirtualBox. If you are working with Linux, Vagrant can optionally be used in conjunction with these, while VirtualBox is the standard choice if your DaDesktop machine is running Windows 10.

Based on extensive testing, our recommended approach is to use Virt Manager. We have identified several bugs associated with using VirtualBox in this context; consequently, we currently do not recommend VirtualBox for this specific purpose.

The VirtManager application leverages the libvirt library to deliver virtual machine management services. Its desktop interface simplifies the creation, deletion, and management of multiple virtual machines. While it is primarily designed for KVM VMs, it also supports other hypervisors, including Xen and LXC.

Virt Manager integrates seamlessly with Vagrant. You can install the necessary integration with the following command:

apt install vagrant-libvirt

Please note that while there are fewer Vagrant boxes available for libvirt/kvm compared to VirtualBox, existing boxes can be easily converted to work with libvirt, as demonstrated here:

https://medium.com/@gamunu/use-vagrant-with-libvirt-unsupported-boxes-12e719d71e8e

The user interface offers a comprehensive overview of all VMs, displaying their status, CPU usage, live performance graphs for running instances, and resource utilization statistics.

If you are new to Virt Manager, you will find the experience familiar if you have used VirtualBox, though there are several key differences detailed below.

For a reliable guide on using virt-manager on Ubuntu Linux, refer to the following resource: https://www.debugpoint.com/virt-manager/

Why choose Virt Manager over VirtualBox?

Advantages

1. Superior Performance – Virt Manager utilises VirtIO drivers for storage, networking, and graphics, resulting in significantly better performance. VirtIO drivers are KVM’s paravirtualized device drivers, available for Linux and Windows guest virtual machines running on KVM hosts. The virtio package supports block (storage) devices, network interface controllers, and graphics. As these drivers are open source, they can be easily installed if not pre-installed on your Linux distribution.
2. A wider range of configurability options is available.
3. Seamless integration with Vagrant.
4. Unlike VirtualBox, which has components that are not fully open source, Virt Manager is fully open source.
5. Virt Manager eliminates the need for module recompilation after kernel upgrades, a requirement for VirtualBox.
6. VirtualBox is known to occasionally become unstable following kernel upgrades.

Disadvantages

1. VirtualBox may offer a slightly shorter learning curve.
2. Configuring 'Host networking' rather than NAT is generally more straightforward in VirtualBox. However, NAT functions adequately for most networking use cases in both systems.
3. While VirtualBox is available across many platforms, Virt Manager is exclusively available on Linux.

Overall, we find Virt Manager to be the preferred solution for running servers within a DaDesktop environment.

Installation

Given that libvirt is continuously evolving, it is best practice to use the latest non-LTS version of Ubuntu or Debian.

To install kvm and virt-manager, please follow the latest guide suited to your preferred DaDesktop OS. While the following are brief installation notes, a comprehensive guide can be found here: https://www.debugpoint.com/virt-manager/

sudo apt install virt-manager

sudo adduser student libvirt
sudo systemctl restart libvirtd

Restart your DaDesktop machine, then launch Virt Manager from the Applications menu.

Configuration

1. Importing or Converting Virtual Machines While creating new VMs tailored to specific operating systems and specifications is straightforward, complex setups often benefit from importing existing VM configurations for specific servers or appliances. These are frequently provided as VMDK images. Although adding these directly to Virt Manager may not be fully supported in the current version, VirtualBox server images can be easily exported into formats such as Open Virtualisation Format (.OVF), which Virt Manager can import. Alternatively, you can use VMware Converter (if available) or Virt-V2V. Qemu-convert is another excellent open-source tool for converting between different virtual machine formats.
   To convert from VirtualBox to Virt Manager KVM format, follow the instructions available here: https://ostechnix.com/how-to-migrate-virtualbox-vms-into-kvm-vms-in-linux/

2. Importing Large Files into Standalone Environments. A new feature now allows for the easy upload of files from your local machine to your DaDesktop environment.

   Alternatively, you can use cloud storage tools like Google Drive or Microsoft 365. These services can be accessed by logging in from within the DaDesktop machine.

3. Adjusting Graphics and Disk Types During Import. When importing virtual machines from other formats, you may need to modify the graphics and/or disk types. A major advantage of Virt Manager is its robust support for VirtIO drivers. These open-source, fully virtualised drivers offer significantly better performance than legacy disk, network, or graphics drivers and are available for nearly all operating systems, including excellent support for Windows 10 guests. If your Guest OS supports them, VirtIO drivers are generally the preferred choice for compatibility and performance when using Virt Manager (KVM). See: https://wiki.archlinux.org/title/Libvirt
4. Optimal Virtual Machine Settings in Virt Manager. VirtIO drivers are included in almost all modern open-source server operating systems and can be easily installed on Windows. While virtio is generally the best driver choice, other types may be necessary in specific cases. NAT networking is sufficient for most scenarios unless a more complex setup requiring Bridged Host networking is needed, though the latter can be more challenging to configure. A helpful starter guide is available here: https://wiki.archlinux.org/title/Virt-manager. Running Windows requires additional steps, specifically slipstreaming VirtIO drivers to ensure the Windows 10 ISO can boot. Regarding hard disk formats, .raw files offer the best speed, but qcow2 format should be used if snapshots are required, accepting a slight performance trade-off.
5. Although Wayland functions well as a display manager in many cases, we advise continuing to use X11 for now. However, it may be worthwhile to test Wayland in your specific setup, as distribution support for Wayland is improving steadily.
6. We advise against using ksm; while it works in nested and Virt Manager environments, it offers little practical difference in performance.
7. Tech Support is available for assistance with converting disk images for Virt Manager compatibility and for setting up Virt Manager for DaDesktop courses.

8. Locating Disk Image Files. Virt Manager stores image files in the following location by default, though this path is configurable if you prefer an alternative directory:

   /var/lib/libvirt/images