How to Create a Virtual Machine with KVM on Ubuntu 20.04

In this tutorial, we will guide you through the process of creating a virtual machine (VM) using KVM (Kernel-based Virtual Machine) on Ubuntu 20.04. KVM is a virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. This method is widely used due to its performance and efficiency.

Prerequisites

• Ubuntu 20.04 installed on your system.
• Minimum of 2GB RAM (4GB recommended) and sufficient disk space.
• Root or sudo privileges on your Ubuntu machine.
• Familiarity with terminal commands and basic Linux operations.

Main Steps

1. Install KVM and Required Packages

To get started, you need to install KVM along with some additional packages. Open your terminal and run the following command:

sudo apt update
sudo apt install -y qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils

After the installation is complete, verify that KVM is installed correctly by checking the status:

sudo systemctl status libvirtd

You should see a message indicating that the service is active (running).

2. Add Your User to the KVM Group

To allow non-root users to manage VMs, add your user to the 'kvm' group. Replace with your actual username:

sudo adduser  kvm

Log out and back in for the group changes to take effect. You can verify your group memberships by running:

groups

3. Verify KVM Installation

Use the following command to check if your CPU supports virtualization:

egrep -c '(vmx|svm)' /proc/cpuinfo

If the output is greater than 0, your CPU supports virtualization.

4. Create a Virtual Machine

You can create a new VM using the virt-install command. Let’s create an Ubuntu 20.04 VM:

sudo virt-install \
--name UbuntuVM \
--os-variant ubuntu20.04 \
--vcpus 2 \
--memory 2048 \
--disk path=/var/lib/libvirt/images/ubuntu_vm.img,size=20 \
--network network=default \
--graphics none \
--cdrom /path/to/ubuntu-20.04-desktop-amd64.iso

Adjust the parameters such as --vcpus, --memory, and --disk according to your requirements.

5. Access the Virtual Machine

You can access the VM through a console or a VNC viewer. Use the following command to connect via a console:

sudo virsh console UbuntuVM

To detach from the console, press Ctrl+].

Advanced Configuration

After creating the VM, you may want to configure additional settings such as network bridges or storage options.

1. Network Configuration

For advanced networking, you may want to create a bridge. Edit the netplan configuration:

sudo nano /etc/netplan/01-netcfg.yaml

Then define your bridge configuration as follows:

network:
version: 2
renderer: networkd
ethernets:
eth0:
dhcp4: no
addresses: [192.168.1.100/24]
gateway4: 192.168.1.1
nameservers:
addresses: [8.8.8.8, 8.8.4.4]
bridges:
br0:
interfaces: [eth0]
dhcp4: yes

Apply the changes with:

sudo netplan apply

2. Storage Configuration

If you need additional storage, you can create a new disk for your VM:

sudo qemu-img create -f qcow2 /var/lib/libvirt/images/ubuntu_vm_data.img 20G

And then attach it to the VM using:

sudo virsh attach-disk UbuntuVM /var/lib/libvirt/images/ubuntu_vm_data.img vdb --driver qemu --subdriver qcow2 --persistent

Best Practices

• Regularly back up your VMs and their configurations.
• Monitor resource usage to avoid performance issues.
• Use snapshots before making major changes to the VM.
• Keep your system updated to benefit from performance and security improvements.

Troubleshooting

In case you encounter issues while creating or managing your VMs, here are some common troubleshooting steps:

• Permissions Issue: Ensure that your user is part of the 'kvm' group.
• Network Problems: Check your bridge configuration and ensure it matches your network settings.
• VM Won't Start: Review the logs with sudo journalctl -xe for any errors during startup.

Conclusion

Creating a virtual machine using KVM on Ubuntu 20.04 is a powerful way to leverage virtualization for various applications. With this guide, you should be able to set up a VM easily and explore advanced configurations as needed. Always remember to follow best practices to maintain a healthy virtual environment.

For further assistance or custom setups, feel free to consult our setup services.