In Proxmox, “resizing a disk” means adjusting the logical capacity of the VM’s virtual drive. You do this to give a VM more space (expand). In this guide, we shall discuss how to resize or Expand Proxmox Hard Drive. Please, see How to delete a VM and Storage in Proxmox, How to extend a VM Hard Disk on VMware Workstation, and how to Create a bootable USB on Mac: Proxmox VE Setup.
Table of contents
In Proxmox VE, each virtual machine (VM) has one or more virtual disks. This is similar to a physical computer has hard drives. These disks are files or volumes stored on the host’s storage backend. The table below show the common Proxmox disk types.
| Disk Format | Description | Typical Use |
|---|---|---|
| QCOW2 | A flexible disk image file format supporting snapshots and compression. | Used on directory-based storage (e.g. /var/lib/vz/images/...) |
| RAW | A raw binary file, faster but less flexible (no internal snapshots). | For performance-focused setups |
| LVM / LVM-thin | Logical volumes directly created on a volume group (not simple files). | Common for local SSD/HDD storage; managed by Proxmox automatically |
| ZFS volumes (zvols) | Virtual block devices backed by ZFS datasets. | For high performance or redundancy setups |
Also, see how to fix “Unable to update the password value provided for the new password and Password Policy“, and Resolve the Update Package Database failure on Proxmox VE.
Fix Veeam Virtual Appliance requires at least 240 GB
This article “how to setup Veeam Software Appliance v13“, gave birth to this topic. The Veeam Software Appliance requires at least two disks. A 240 GB+ system disk for JeOS, Veeam software, database, and instant recovery cache (recommended 480 GB multi-TB SSD depending on workload size).
And a second 240 GB+ disk for catalogs and backups, with any extra disks automatically merged into a single LVM volume. For “Veeam Infrastructure Appliance”, the requirements are different!
Note: Experienced administrators fall into the habit of skipping documentation when testing or deploying new technologies, relying instead on prior knowledge. While experience is valuable, this practice can lead to overlooked prerequisites, unsupported configurations, or subtle compatibility issues.
Following official guides and verified documentation should remain standard procedure and not as a sign of inexperience. But as a mark of professionalism and due diligence. Consistency in adhering to vendor recommendations ensures accuracy, repeatability, and long-term stability across environments.
Please, see What is taking up by Synology NAS Volume Space, how to Download and update Synology DiskStation NAS to DSM 7.3, and how to Patch Veeam Backup and replication 12.3.2.3617 to 12.3.2.4165.
Precaution to Take
Before performing any disk resize operation, create and verify a full VM backup or snapshot. This step is mandatory. A validated backup ensures data recoverability in case of corruption, misconfiguration, or unexpected failure during the resize process.
Once the backup is confirmed, proceed to expand the virtual disk at the hypervisor level using the appropriate Proxmox interface (GUI or CLI). This approach provides a controlled rollback point and eliminates the risk of irreversible data loss.
Here is How to install Pleasant Password Server, and how to perform Offline and Online Update for Object First Out-of-the-Box Cluster.
Resize (Expand) Hard Disks
To do this, Log in to the Proxmox Web GUI. In the left pane, select the Proxmox node if you have multiple nodes in your Datacenter. Then select the VM you want to modify.
Next, In the top menu tabs, click Hardware and click on each disk as shown below. Afterwards, use the dropdown menu associated with the Disk Action and select Resize.
In the resize disk, enter the size of the increment. Just to satisfy the VSA requirements, I am adding 120 GB more. I will eventually add more to make it 256 GB just for my personal requirements.
After entering the new value, click on resize as shown below.
As you can see, the disks have been resized sucessfully.
Please, see how to set up the OOTBI Virtual Appliance on Proxmox VE, and how to shrink and create new partition on Windows Server.
Shrining Proxmox Disks
To shrink the virtual disk in Proxmox is not so straight forward. This is because, Proxmox cannot directly shrink raw/QCOW2 disks safely unless the filesystem inside has been reduced first. Since this is not the focus of this article, I will only discuss not in detail
The recommended approach is tor educe the partition and filesystem inside the guest (using resize2fs or equivalent for ext4/xfs).
qm disk resize <vmid> scsi0 60GAs noted for resizing, always back up or snapshot before shrinking disks in Proxmox.
Optional step: Shrinking is destructive if done incorrectly. Next, compact the disk to reclaim unused blocks if it is QCOW2.
qemu-img convert -O qcow2 olddisk.qcow2 newdisk.qcow2Alternatively, you could use GParted and Proxmox CLI tools if you are comfortable with live partition editing. Attach GParted ISO and Boot the VM and boot into it. Use GParted to shrink the partition and filesystem graphically. This is often easier and safer than CLI tools for some users. Please take a look at the forum post from Proxmox. You will also find this post very useful.
After shrinking the partition, shut down the VM. Use the Proxmox host CLI to shrink the virtual disk: For example, “QCOW2”. Only if the partition was reduced by at least 10 GB.
qemu-img resize /path/to/disk.qcow2 -10GOptional, compact QCOW2 Disk to reclaim unused space. After this is done, replace the disk if needed and boot the VM to verify everything works.
qemu-img convert -O qcow2 shrunk.qcow2 compacted.qcow2I hope you found this guide useful on how to resize or expand Proxmox Hard Drive. Please, feel free to lave a comment below.
