Creating Virtual Disks with qemu-img: Step-by-Step Guide

Virtualization is a fundamental concept in modern computing that allows you to create and manage virtualized environments, enabling multiple operating systems to run on a single physical machine. QEMU (Quick EMUlator) is a versatile and powerful open-source virtualization tool that provides various features for creating and managing virtual machines. One of the key components of QEMU is qemu-img, a command-line tool used for creating, converting, and managing disk images for virtual machines. In this tutorial, we’ll explore how to use qemu-img to create virtual disks for your virtual machines.


Before we dive into creating virtual disks, make sure you have QEMU and qemu-img installed on your system. If not, you can install them by following the instructions for your specific operating system.

Checking QEMU Installation

To verify if QEMU is installed, open a terminal window and enter the following command:

qemu-system-x86_64 --version

If QEMU is installed, this command will display the version information; otherwise, you need to install it.

Installing qemu-img

qemu-img is usually included as part of the QEMU package. To ensure you have it, you can execute:

qemu-img --version

If the command reports the version, you’re all set. Otherwise, install QEMU or the necessary package for your distribution.

Creating a Virtual Disk

Now that we have QEMU and qemu-img ready, let’s start by creating a virtual disk. Virtual disks are essential for storing the operating system, applications, and data of your virtual machine.

Choosing the Disk Format

QEMU supports various disk formats, such as raw, qcow2, vmdk, and more. Each format has its advantages and use cases. For instance, the raw format provides better performance, while qcow2 offers advanced features like snapshots and compression.

To create a virtual disk in a specific format, you can use the following command syntax:

qemu-img create -f <format> <disk_name>.<extension> <size>

Replace <format> with your desired format, <disk_name> with the desired name of your virtual disk, <extension> with the appropriate file extension for the chosen format, and <size> with the size of the disk (e.g., 10G for 10 gigabytes).

Let’s say you want to create a 20GB virtual disk in the qcow2 format named “mydisk.qcow2.” You would use the following command:

qemu-img create -f qcow2 mydisk.qcow2 20G

With this command, you’ve successfully created a virtual disk in the qcow2 format.


In this tutorial, we’ve covered the basics of creating virtual disks using qemu-img. We started by ensuring QEMU and qemu-img were installed on our system, then proceeded to create a virtual disk in a specific format. Remember that these are just the fundamentals, and QEMU offers a wide range of options and capabilities for managing virtual machines and their disk images. With this knowledge, you’re now equipped to create and manage virtual disks efficiently for your virtualized environments.

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