Missing feature: Show free internal diskspace of VM

D

Dd1

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Mar 9, 2026
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Hi there,

since more than 20 years administering a vSphere environment in conjunction with Veeam B&R/ONE and am therefore spoiled when it comes to alerts, etc.
I miss several convenient features, such as alerts when a (Windows or Linux) VM is running low on disk space.
I haven't been able to find any such information on the PVEs despite having "VM-Tools"-like applications like QEMU installed.

Does anyone have any suggestions on how to achieve this (besides creating a separate disk space warning system for each VM)?

Rgds,

Dietmar
 
Use a monitoring tool like Zabbix, Icinga, Prometheus or prtg. I'm a bit baffled that somebody could do twenty years without it. I couldn't do my work without the monitoring and alarming features of a Icinga since the Hypervisor ( no matter which one) is quite limited in that regard
 
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Hi Dietmar,

I wanted to contribute a couple of points regarding the visibility of internal disk usage.

First, it's worth noting that Proxmox already implements this feature for LXC Containers (CT). As shown in the summary page for a container, Proxmox can natively display the "Bootdisk size" along with the percentage of internal usage. It would be great if a similar integration could be brought to VMs via the QEMU Guest Agent.

2026-03-10_12-23 ct.png

For those looking for a solution for VMs right now, I’ve been using a monitoring tool called Pulse ( https://github.com/rcourtman/Pulse ). By installing a small agent on the guest OS (VMs), it allows you to:
  1. View real-time internal disk usage across multiple hosts.
  2. Set up automated alerts for high disk usage (defaulting to 90%).

2026-03-10_12-21pulse.png

While we wait for a potential native feature in the Proxmox UI, using an external dashboard like Pulse has been a very effective workaround for my environment.
 
PVE cannot determine the free disk space inside the VM from the outside easily.
It would have to detect and parse the disk partition table and then read the filesystem metadata.
This stuff is trivial inside the VM, because there you have all the OS drivers etc loaded, the disks mounted etc.

So the only way I see how is this possible if the Qemu Guest Agent reports the free disk space to the PVE host and then the host could display it. Youd have to talk to the developers of the guest agent in order to implement this though.
 
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Impact said:
This is already available. Proxmox just has to integrate it. Try something like this
Bash: 
qm guest cmd VMID get-fsinfo | jq
You can see what that looks like here.

I also searched the bug tracker for get-fsinfo (I couldn't remember the command earlier) and these reports are relevant/related
- https://bugzilla.proxmox.com/show_bug.cgi?id=1373
- https://bugzilla.proxmox.com/show_bug.cgi?id=1592
Click to expand...

Wow, I'm learning this for the first time! This is a very useful command.

After testing it out (as shown in my output below), I can confirm that it provides detailed usage statistics for multiple disks or partitions within the VM. In my case, it correctly identified /boot/efi along with its total and used bytes.

2026-03-10_17-13.png

However, it’s worth noting that for this to work:
  1. The QEMU Guest Agent must be installed and enabled within the guest OS.
  2. The VM must be running at the time of the query.
It would be fantastic if the Proxmox team could eventually leverage this existing API to display these metrics directly in the Summary UI!
 
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