Managing virtual machine storage is a critical skill for any Proxmox administrator. In this guide, you will learn how to resize VM disks for Windows 10, Windows Server, and Ubuntu without disrupting your running VMs. The tutorial covers all steps clearly, including checking disk usage, expanding virtual disks, and resizing partitions inside the operating system. Following these instructions will help prevent downtime and data loss while maximizing your VM storage capacity. This step-by-step approach is ideal for both beginners and experienced sysadmins. You will also learn how to troubleshoot common issues that may arise during the resizing process. With proper VM disk management, your Proxmox environment becomes more flexible and efficient for daily workloads. Follow along to confidently expand VM storage and keep your virtual infrastructure running smoothly.

1. VM Ubuntu

Step 1: Increase size on GUI
Enter the number of Gb to increase

Step 2: Install the partition extension tool
sudo apt update
sudo apt install cloud-guest-utils -y

Step 3: Expand the partition
sudo growpart /dev/sda 3
Purpose: Expand partition number 3 (/dev/sda3) to take up all the free space on disk /dev/sda
Expand LVM Physical Volume (PV)
sudo pvresize /dev/sda3

Expand Logical Volume (LV)
Run the command:
sudo lvextend -l +100%FREE /dev/mapper/ubuntu–vg-ubuntu–lv
(This command uses up all the free space of the PV.)

Step 4: Expand the filesystem
If you use ext4 (Ubuntu default). Check again with command: df -h
sudo resize2fs /dev/mapper/ubuntu–vg-ubuntu–lv
Check again:
df ​​-h

2. VM Windows 10

Step 1: Increase size on GUI
Enter the number of Gb to increase

Step 2: Install Minitool partition
Move/Resize system partition to the right.
Extend size

3. VM Windows Server

Step 1: Increase size on GUI
Enter the number of Gb to increase
Step 2: Open File and storage service
Volume  Disk  Select drive C extend volume (enter max capacity)