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Setting Up VMs Inside DaDesktop with Virt Manager

Getting Started

When putting together a course, it's handy to run a virtual server inside DaDesktop, and sometimes a couple of client VMs too—whether they share the same OS or combine Windows and Linux.

You can run Nested VMs either with Virt Manager, or using VirtualBox (optionally with Vagrant on Linux). On Windows 10, VirtualBox is your go-to for DaDesktop.

DD Machines Nested Virt

After thorough testing, we recommend Virt Manager over VirtualBox because the latter has a few bugs in this setup. So for now, we advise against using VirtualBox for nested virtualization.

Virt Manager relies on the libvirt library to handle VM management. Its desktop GUI makes it easy to create, remove, and oversee multiple virtual machines. While it's mainly built for KVM VMs, it also works with other hypervisors like Xen and LXC.

Virt Manager pairs smoothly with Vagrant—just run: 

apt install vagrant-libvirt

It's worth noting that there are fewer Vagrant boxes available for libvirt/kvm than for VirtualBox, but you can convert them to libvirt format easily—see this guide:

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

The UI gives you an at-a-glance summary of all your VMs—status, CPU usage, live performance graphs for running machines, and resource utilization stats.

If you're new to Virt Manager, it's much like VirtualBox, but there are some key differences, which we'll cover next.

Need a good tutorial on virt-manager for Ubuntu? Here's a handy one: https://www.debugpoint.com/virt-manager/

 

Why Opt for Virt Manager Rather Than VirtualBox?

Advantages
  1. Speed is noticeably better—Virt Manager leverages VirtIO drivers for storage, networking, and graphics, which dramatically boosts performance. Virtio drivers are KVM's paravirtualized device drivers, compatible with both Linux and Windows guest VMs on KVM hosts. They handle block (storage) devices, network interface controllers, and graphics. Being open source, VirtIO drivers are a breeze to install if they're not already built into your Linux distribution.
  2. You get more configuration options.
  3. Pairs nicely with Vagrant.
  4. Some components of VirtualBox aren't entirely open source.
  5. Unlike VirtualBox, Virt Manager doesn't require you to recompile modules every time you upgrade the kernel.
  6. VirtualBox sometimes breaks after a kernel upgrade.
Disadvantages
  1. VirtualBox might have a slightly gentler learning curve.
  2. Configuring host networking instead of NAT is simpler in VirtualBox, though NAT handles most networking needs easily on both platforms.
  3. VirtualBox runs on many operating systems, while Virt Manager is Linux-only.


Overall, for running servers inside DaDesktop, Virt Manager is our top pick.

 

Installation

Since libvirt is constantly evolving, stick with the latest non-LTS Ubuntu or Debian release.

To install KVM and virt-manager, here are the bare essentials—but do follow a current guide tailored to your DaDesktop OS. For example, check this one out: 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 Creating VMs from scratch in your chosen OS and specs is straightforward, but for more complex configurations, you'll often want to import an existing VM—like a specific server or appliance. These commonly come as VMDK images, which can sometimes be added directly to Virt Manager, though whether the current version supports this isn't entirely clear. VirtualBox server images, on the other hand, can't be imported directly. You can, however, export them to other virtualization formats such as the Open Virtualization Format (.OVF), which Virt Manager can easily import. Alternatively, you can use VMware Converter if you have it, or Virt-V2V (see https://www.redhat.com/en/blog/importing-vms-kvm-virt-v2v). Qemu-convert is another excellent open source tool for converting between different VM formats.
    To convert from VirtualBox to Virt Manager's KVM format, follow these steps: https://ostechnix.com/how-to-migrate-virtualbox-vms-into-kvm-vms-in-linux/

  2. The best way to import large files when running standalone. A new feature now lets you upload files from your local machine straight into your DaDesktop environment with ease.

    Alternatively, you can turn to cloud storage like Google Drive, Microsoft 365, and similar—just log into those services inside the DaDesktop machine.

  3. When importing VMs, especially from other formats, you'll often need to adjust the graphics and/or disk types. One major plus of Virt Manager is its excellent VirtIO driver support. These open source, fully virtualized drivers deliver far better performance than standard disk, network, or graphics drivers, and they work with nearly every OS—including strong support for Windows 10 guests. Whenever your guest OS can use them, VirtIO drivers are generally the top choice for compatibility and speed in Virt Manager (KVM). Check out https://wiki.archlinux.org/title/Libvirt for more.
  4. Optimal settings when using Virt Manager. VirtIO drivers are bundled with nearly all modern open source server OSes, and they install easily on Windows too. While VirtIO is typically the best-performing driver, you might occasionally prefer another type. For networking, NAT suits most situations; only complex setups call for bridged host networking, which can be trickier to get right. 
    https://wiki.manjaro.org/index.php?title=Virt-manager makes a great starting guide.
    Running Windows requires a few extra steps, including slipstreaming VirtIO drivers so the Windows 10 ISO can boot.
    For disk image formats: raw files offer the best speed unless you need snapshots—in that case, go with qcow2, though it's a bit slower.
  5. While Wayland serves well as a display manager for many scenarios, we recommend sticking with X11 for the time being. Still, it's worth testing Wayland in your own environment, as distro support keeps improving.
  6. You can skip KSM; even though it works nested and within Virt Manager, it doesn't make much practical difference.
  7. If you need help converting disk images for Virt Manager or setting it up for your DaDesktop courses, Tech Support is available.

  8. Wondering where disk image files live on your filesystem? By default, Virt Manager stores them at: 

    /var/lib/libvirt/images