Building VMs within DaDesktop using Virt Manager

Introduction

When developing course materials, it is often beneficial to virtualise a server inside DaDesktop, and potentially one or two client machines as well. This can be achieved using the same operating system or a mix of Windows and Linux environments.

You can run 'Nested VMs' using either Virt Manager or VirtualBox. If using Linux, Vagrant is an optional companion; for Windows 10 DaDesktop machines, VirtualBox is the standard choice.

Based on extensive testing, we recommend Virt Manager. VirtualBox has been found to have several bugs in this context, so we currently advise against using it for nested virtualization in this manner.

VirtManager 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 such as Xen and LXC.

Virt Manager integrates seamlessly with Vagrant using a simple command:

apt install vagrant-libvirt

Please note that the number of Vagrant boxes available for libvirt/kvm is lower than for VirtualBox. However, converting VirtualBox boxes to work with libvirt is straightforward, as demonstrated in this resource:

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

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

If you are new to Virt Manager, it resembles VirtualBox but with key differences outlined below.

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

 

Why choose Virt Manager over Virtualbox?

Benefits

1. Superior performance – Virt Manager utilizes VirtIO drivers for storage, networking, and graphics, delivering significantly better efficiency. Virtio drivers are KVM paravirtualized device drivers available for Linux and Windows guest VMs on KVM hosts. The virtio package supports block (storage) devices, network interface controllers, and graphics. As an open-source solution, VirtIO drivers can be easily installed if not pre-installed on your Linux distribution.
2. Greater configurability options
3. Seamless integration with Vagrant
4. Some components of VirtualBox are not fully open source
5. Virt Manager eliminates the need for module recompilation after kernel upgrades, a common requirement for VirtualBox.
6. VirtualBox may occasionally become unstable following kernel upgrades.

Limitations

1. VirtualBox may offer a slightly gentler learning curve
2. Configuring 'Host networking' (rather than NAT) is generally simpler in VirtualBox, although NAT functions well for most networking scenarios on both platforms.
3. VirtualBox is available across many platforms, whereas Virt Manager is exclusively available on Linux

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

 

Installation

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

To install kvm and virt-manager, refer to the following brief instructions. However, for the most up-to-date steps, please consult a current guide 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

Reboot the DaDesktop machine and launch Virt Manager from the Applications menu.

 

Configuration

1. How can I import or convert virtual machines ? While creating VMs tailored to your OS and specification requirements is straightforward, importing existing server or appliance setups is often preferable for complex environments. These are typically provided as VMDK images. Although direct addition to Virt Manager may not be fully supported in current versions, VirtualBox server images can be easily exported to formats like Open Virtualisation Format (.OVF), which Virt Manager imports seamlessly. Alternatively, you can use VmWare Convertor or Virt-V2V (https://www.redhat.com/en/blog/importing-vms-kvm-virt-v2v). Qemu-convert is also an 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. Optimal method for importing large files into a standalone environment. A new feature allows you to easily upload files from your local machine into your DaDesktop machine.

   Alternatively, consider using cloud storage services like Google Drive or Microsoft 365. You can access these tools by logging in within the DaDesktop machine.

3. When importing VMs from other formats, you may need to adjust 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 standard disk, network, or graphics drivers and are compatible with nearly all operating systems, including excellent support for Windows 10 guest machines. If your Guest OS supports them, VirtIO drivers are the preferred option for both compatibility and performance when using Virt Manager (KVM). See https://wiki.archlinux.org/title/Libvirt for details.
4. Optimal settings for virtual machines using Virt Manager VirtIO drivers are now included in most open-source server operating systems and can be easily installed on Windows. Generally, virtio drivers are the best choice, though other types may be necessary in specific cases. For networking, NAT is sufficient for most scenarios unless a more complex setup requires Bridged Host networking, which can be more challenging to configure. 
   https://wiki.archlinux.org/title/Virt-manager is an excellent starter guide.
   Running Windows  requires additional steps, including slipstreaming VirtIO drivers to ensure the Windows 10 ISO boots correctly.
   When selecting the hard disk format, .raw files offer the best speed unless snapshots are required; in that case, use the qcow2 format, which is slightly slower.
5. Although Wayland functions well for most display management cases, we recommend continuing to use X11 for the time being. However, it is worth testing Wayland in your specific setup, as distributions are improving Wayland support regularly.
6. There is little practical benefit to using ksm, even though it works in nested environments and with Virt Manager.
7. Tech Support is available if you require assistance with converting disk images for Virt Manager compatibility or setting up Virt Manager for DaDesktop courses.

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

   /var/lib/libvirt/images