---
title: Resize an existing virtual disk
description:
published: true
date: 2026-05-08T09:34:59.946Z
tags:
editor: markdown
dateCreated: 2021-11-13T11:41:29.087Z
---
# Resize a virtual disk
## Background
A virtual machine's disk may have to be resized, typically due to lack of space. This page explains how to do so.
## Preparation
### Shut down virtual machine
> Please ensure that the virtual machine using the virtual disk to be resized is turned off
{.is-warning}
Let's assume that you wish to increase the size of the virtual machine called *guest*.
- List virtual machines running on your host
```
# virsh list --all
Id Name State
----------------------------------------------------
1 guest running
```
- Shutdown the *guest* virtual machine
```
# virsh shutdown guest
```
- Ensure that the virtual machine is fully shut off
```
# virsh list --all
Id Name State
----------------------------------------------------
1 guest shut off
```
It is now safe to proceed to the next step
### Backup existing disk
It is advisable to make a backup first.
- Navigate to the correct directory
```
# cd /var/lib/libvirt/images
```
- Make a copy of the virtual disk image
```
# cp guest.img backup_guest.img
```
## Linux guests
> In-place expansion is not supported. A new disk of the desired size has to be created, and then swap with the former disk.
{.is-info}
- Navigate to the location that contains the existing image
```
# cd /var/lib/libvirt/images
```
- Create a new blank 20 GB disk called `guest_20G.img`
```
# qemu-img create -f raw guest_20G.img 20G
```
- Identify the filesystem layout of the existing disk `guest.img`, which is ext4-based
```
# virt-filesystems -a guest.img -l -h
Name Type VFS Label Size Parent
/dev/vda1 filesystem vfat EFI 1.3G -
/dev/vda2 filesystem ext4 boot 3.6G -
/dev/vda3 filesystem ext4 root 10G -
```
- Another output for a btrfs-based filesystem
```
# virt-filesystems -a bazzite-desktop.img -l -h
Name Type VFS Label Size Parent
/dev/sda1 filesystem vfat - 599M -
/dev/sda2 filesystem ext4 bazzite_xboot 1.9G -
/dev/sda3 filesystem btrfs bazzite 37G -
btrfsvol:/dev/sda3/root filesystem btrfs bazzite - -
btrfsvol:/dev/sda3/home filesystem btrfs bazzite - -
btrfsvol:/dev/sda3/var filesystem btrfs bazzite - -
```
Thanks to the label on the ext4-based based image, one can tell that the root partition is `/dev/vda3`. This is the one that will need to be expanded. For the btrfs example, the root partition `/dev/sda3`as shown by `btrfsvol:/dev/sda3/root`
* Copy the former old data to the new disk and expand the root partition of the said disk
> This command is capable of expanding different kinds of filesystems, including `ext4` and `btrfs`
{.is-info}
The command takes the new empty disk as last argument.
> Data could be erased if you mix argument!
{.is-warning}
```
# virt-resize --expand /dev/vda3 guest.img guest_20G.img
```
* Review changes
```
[ 0.0] Examining guest_20G.img
**********
Summary of changes:
/dev/vda1: This partition will be left alone.
/dev/vda2: This partition will be left alone.
/dev/vda3: This partition will be resized from 10G to 20G. The
filesystem ext4 on /dev/vda3 will be expanded using the ‘resize2fs’
method.
**********
[ 2.1] Setting up initial partition table on guest_20G.img
[ 12.9] Copying /dev/vda1
[ 13.1] Copying /dev/vda2
[ 13.4] Copying /dev/vda3
100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00
[ 38.3] Expanding /dev/vda3 using the ‘resize2fs’ method
Resize operation completed with no errors. Before deleting the old disk,
carefully check that the resized disk boots and works correctly.
```
* Switch to the new disk for your virtual machine
Now that the new disk has been created, it can be used in the virtual machine.
```
# virsh edit guest
```
Locate the source line for the existing disk `guest.img`:
```
[...]
[...]
```
Edit the said line so that it points to the new disk `guest-20G.img`:
```
[...]
[...]
```
Start the virtual machine and ensure that it is working properly. If it does, the former disk could be removed.
## Resources
As per the software description : "*qemu-img allows you to create, convert and modify images offline. It can handle all image formats supported by QEMU.*"
* Installation
On Fedora-related distributions, `virt-resize` is provided by the `guestfs-tools` package :
```
# dnf install guestfs-tools
```
---
*[**Go to parent page**](https://wiki.phyllo.me/)*