Resize disk in Proxmox VM

I needed to resize a disk in my Proxmox VM. Specifically, I was working with a Debian 12 (Bookworm) VM created through Proxmox VE Helper Scripts. These VMs come with a default size of 2 GB, even when using the advanced installation option. Unfortunately, there’s no way to select the disk size during the initial installation process.

Pre-Requisites

First, install the required tools:

apt install parted fdisk

Steps to Resize the disk

  • Resize the disk through Proxmox GUI.

  • Login to the VM and run fdisk -l . You should see warnings similar to:

GPT PMBR size mismatch (167772159 != 314572799) will be corrected by write. The backup GPT table is not on the end of the device. This problem will be corrected by write.

  • Use parted to fix the partition table:
parted /dev/sda

print

You’ll see a warning:

Warning: Not all of the space available to /dev/sda appears to be used, you can fix the GPT to use all of the space (an extra 146800640 blocks) or continue with the current setting?

  • Fix the partition table
Fix/Ignore? F
  • Resize the partition:
(parted) resizepart 1
Warning: Partition /dev/sda1 is being used. Are you sure you want to continue?
Yes/No? y
End? [85.9GB]? 100%
quit
  • Apply the changes to the filesystem:
resize2fs /dev/sda1

Note: This method works only for ext4 non-LVM filesystems.