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Introduction to Virtualization with KVM/QEMU on Linux
Virtualization is a powerful technology that allows you to create and manage virtual machines (VMs) on a single physical server. KVM (Kernel-based Virtual Machine) and QEMU (Quick EMUlator) are popular tools in the Linux ecosystem for setting up and managing virtual environments. This tutorial will guide you through the basics of virtualization using KVM and QEMU.
Prerequisites
- A Linux distribution with a kernel that supports KVM (typically versions >= 2.6.20).
- Root or sudo privileges to install software and configure the system.
1. Installing KVM and QEMU
First, ensure that your system supports hardware virtualization. You can check if KVM is supported by running:
egrep -c '(vmx|svm)' /proc/cpuinfoIf the output is greater than 0, your CPU supports hardware virtualization. Next, install KVM and QEMU along with necessary utilities:
- For Ubuntu/Debian:
sudo apt update sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils -y - For CentOS/RHEL:
sudo yum install qemu-kvm libvirt libvirt-python libguestfs-tools -y - For Fedora:
sudo dnf install qemu-kvm libvirt -y
2. Starting and Enabling the Libvirt Service
After installation, start the Libvirt service to manage KVM virtual machines:
sudo systemctl start libvirtd
sudo systemctl enable libvirtd3. Adding Your User to the KVM Group
Add your user to the kvm group to manage virtual machines without root privileges:
sudo usermod -aG kvm $(whoami)Log out and log back in for the changes to take effect.
4. Creating a Virtual Machine
You can create a virtual machine using the virt-install command. Here’s an example command that sets up a virtual machine with a disk, memory, and installation from an ISO file:
sudo virt-install --name myvm --ram 2048 --disk path=/var/lib/libvirt/images/myvm.img,size=10 --vcpus 2 --os-type linux --os-variant ubuntu20.04 --network network=default --graphics none --cdrom /path/to/ubuntu-20.04.isoReplace /path/to/ubuntu-20.04.iso with the path to your installation ISO file.
5. Managing Virtual Machines
To manage and view your running virtual machines, you can use the virsh command interface:
- List all VMs:
virsh list --all - Start a VM:
virsh start myvm - Shutdown a VM:
virsh shutdown myvm - Pause/Resume a VM:
virsh suspend myvm virsh resume myvm - Delete a VM:
virsh undefine myvm
6. Using Graphical Tools
For those who prefer graphical interfaces, you can use tools like virt-manager. To install virt-manager:
- For Ubuntu/Debian:
sudo apt install virt-manager -y - For CentOS/RHEL:
sudo yum install virt-manager -y - For Fedora:
sudo dnf install virt-manager -y
Launch virtue-manager from the application menu to manage your virtual machines graphically.
7. Conclusion
By using KVM and QEMU, you can harness the power of virtualization on Linux to run multiple virtual machines on a single physical server. This guide has covered the installation and basic usage of these tools to get you started with virtualization. As you become more familiar, explore advanced features and configurations for better performance and management.
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