Creating VMs within DaDesktop using Virt Manager

Introduction

When preparing courses, it is often beneficial to virtualize a server within DaDesktop. Similarly, one or two client machines can be virtualized using the same operating system or a combination of Windows and Linux.

Creating Nested VMs is achievable via Virt Manager or VirtualBox. On Linux, Vagrant can optionally be used, while on Windows 10 DaDesktop machines, VirtualBox is the standard approach.

Based on extensive testing, our recommended approach is to use Virt Manager, as VirtualBox presents certain bugs; consequently, we currently do not recommend using VirtualBox in this context.

The VirtManager application utilizes the libvirt library to deliver virtual machine management services. It features a desktop interface designed to facilitate the creation, deletion, and management of multiple virtual machines. While primarily intended for KVM VMs, it also supports other hypervisors such as Xen and LXC.

Virt Manager integrates seamlessly with Vagrant, requiring only the following installation:

apt install vagrant-libvirt

It is important to note that while fewer Vagrant boxes are natively available for libvirt/kvm compared to VirtualBox, they can be easily converted for libvirt compatibility as demonstrated in this resource:

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

The user interface offers a comprehensive summary of all VMs, including their status, CPU usage, live performance graphs for active VMs, and resource utilization statistics.

If you are new to Virt Manager, it is functionally similar to VirtualBox but includes several key differences outlined below.

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

Why choose Virt Manager over Virtualbox?

Advantages

1. Superior performance - Virt Manager leverages VirtIO drivers for storage, networking, and graphics, resulting in significantly enhanced performance. Virtio drivers are paravirtualized device drivers for KVM, available for both Linux and Windows guest virtual machines on KVM hosts. The virtio package supports block storage devices, network interface controllers, and graphics. As VirtIO drivers are open source, they can be easily installed if not pre-installed on your Linux distribution.
2. Greater configurability options are available.
3. Excellent compatibility with Vagrant.
4. Certain components of VirtualBox are not fully open source.
5. Virt Manager eliminates the need for module recompilation after kernel upgrades, a requirement for VirtualBox.
6. VirtualBox is occasionally prone to breaking during kernel upgrades.

Disadvantages

1. VirtualBox generally offers a slightly gentler learning curve.
2. Configuring 'Host networking' (as opposed to NAT) is more straightforward in VirtualBox, although NAT functions adequately for most networking scenarios in both systems.
3. VirtualBox supports multiple platforms, whereas Virt Manager is exclusive to Linux.

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

Installation

Given the continuous improvements in libvirt, it is best to use the latest non-LTS version of Ubuntu or Debian.

Install kvm and virt-manager. The following are brief installation notes; however, please follow an up-to-date guide suitable for your specific DaDesktop OS. One recommended guide is https://www.debugpoint.com/virt-manager/

sudo apt install virt-manager

sudo adduser student libvirt
sudo systemctl restart libvirtd

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

Configuration

1. How to import or convert virtual machines? While creating custom VMs to your specifications is straightforward, complex setups often benefit from importing existing server or appliance configurations. These are frequently supplied as VMDK images, which can theoretically be added directly to Virt Manager, though this capability is unclear in current versions. VirtualBox server images cannot be imported directly but can be exported to other virtualization formats, such as Open Virtualisation Format (.OVF), which Virt Manager handles easily. Alternatively, you may use VMware Convertor (if available) or Virt-V2V as described here: https://www.redhat.com/en/blog/importing-vms-kvm-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 these instructions: https://ostechnix.com/how-to-migrate-virtualbox-vms-into-kvm-vms-in-linux/

2. Efficiently importing large files into standalone environments. A feature has recently been added to easily upload files from your local machine to the DaDesktop machine.

   Alternatively, consider using cloud file services like Google Drive or Microsoft 365. These can be accessed by logging into the service within the DaDesktop machine.

3. Adjusting graphics and/or disk types when importing VMs from other formats. A significant advantage of Virt Manager is its robust support for VirtIO drivers. These open-source, fully virtualized drivers offer substantially better performance than original disk, network, or graphic drivers and are compatible with 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). https://wiki.archlinux.org/title/Libvirt
4. Optimal settings for virtual machines in Virt Manager VirtIO drivers are included in most modern open-source server operating systems and can be easily installed on Windows. Generally, virtio is the best choice, though other types may be necessary in specific cases. NAT is typically sufficient for most networking needs, unless a more complex setup requiring Bridged Host networking is needed, which can be more challenging to configure.
   https://wiki.archlinux.org/title/Virt-manager serves as a great introductory guide.
   Running Windows requires additional steps, specifically slipstreaming VirtIO drivers to ensure the Windows 10 ISO boots correctly.
   Regarding hard disk formats, .raw files are best for speed unless snapshots are required, in which case qcow2 format should be used, though it is slightly slower.
5. Although Wayland functions well as a display manager in most scenarios, we advise continuing to use X11 for the time being. However, it may be worth testing Wayland in your specific setup, as distributions are increasingly improving Wayland support.
6. Avoid using ksm, as although it works in nested and Virt Manager environments, it provides little practical benefit.
7. Tech Support is available for converting disk images for Virt Manager compatibility and for setting up DaDesktop courses using Virt Manager.

8. Where are disk image files stored in the filesystem? Virt Manager uses the following location for image files by default, though this is configurable to other preferred locations.

   /var/lib/libvirt/images