Cannot make Snapshots of VMs

[patrickob]

I have several Windows 11 VMs running on Proxmox 8.2.4. However, when I go to Snapshots management, I see "The current guest configuration does not support taking new snapshots".


I use the following settings:
BIOS: OVMF (UEFI)
Machine: q35-9.0
HDD (SCSI): QCOW2, cache=writeback, discard=on, iothread=1, size=164G
EFI disk and TPM enabled
QEMU Guest Agent enabled
Windows 11/2022/2025

Is there a specific setting that I should (not) have to be able to take snapshots? Or has this something to do with the fact that the size of the virtual HDD is quite large?

Thanks for any help!

 

[carles89]

Hi,

It seems you're using file-based storage, which only supports snapshots with qcow2 disks [1].

The VM disk is in qcow2 format, EFI disk can be in qcow2 too, but AFAIK TPM disk is always in raw format, which is preventing you from taking snapshots [2][3].

If that's the case, the only solution would be to either move to a storage supporting snapshots at filesystem-level (i.e. lvm-thin, ZFS...) or try the solution in [2], which is kind of tricky.

[1] https://pve.proxmox.com/wiki/Storage
[2] https://forum.proxmox.com/threads/tpm-state-and-snapshots.118921/
[3] https://forum.proxmox.com/threads/t...not-support-taking-new-snapshots.73944/page-3

 

[patrickob]

Thanks for that answer! It clears things already up a bit, as it indeed is the TPM that is in raw format and the rest in QCOW2.

However, I am new to Proxmox, so pardon the stupid question. I remember choosing somewhere the filesystem-level, and I think I chose ZFS. Is this only at first install that this can be set?

As I understand from the answer, using TPM would make it impossible to make snapshots, except with the non-ideal workaround of [2]. TPM would be required for Win11. Do I understand this correctly?

 

[carles89]

When you install Proxmox VE, the installer creates two storages by default:

• local (Ext4 filesystem for isos, local backups...)
• local-lvm or local-zfs (depending on what you chose during the installation process.

This cannot be changed without reinstalling, but you can always expand your storage by adding more disks and creating new pools.

Could you share the VM Hardware tab and the contents of Datacenter -> Storage?

I suspect your VM disks may reside in local instead of local-lvm or local-zfs.

 

[carles89]

TPM would be required for Win11. Do I understand this correctly?

Yes indeed, you can install Win11 without TPM using a custom ISO that bypasses the installer requirements (using Rufus), but it's unknown if it may lead to problems in the future.

 

[patrickob]

Here is my VM Hardware tab



I made a separate local, but I think it's not lvm or zfs. Should I simply make a new local with ZFS or LVM? I can purge all VMs as I am still setting up the system.

 

[carles89]

After the initial install, did you have either local-lvm or local-zfs, apart from local? It looks like one of the default storages was manually removed after install.

Should I simply make a new local with ZFS or LVM?

Well, it depends on how many disks you have and how the filesystem looks like.

The simplest way, if you can afford a rebuild, is to reinstall the node from scratch and store your VMs on local-lvm or local-zfs. This way you'll have a "standard" setup and you'll be able to do snapshots.

If you want to try to re-add the storage, please post the contents of the following sections of the GUI to know which storage(s) do you have:

• Datacenter -> Storage
• pve (click on your node) -> Disks
• pve (click on your node) -> Disks -> LVM
• pve (click on your node) -> Disks -> LVM-Thin
• pve (click on your node) -> Disks -> Directory
• pve (click on your node) -> Disks -> ZFS

 

[patrickob]

Here are the contents:

Datacenter->Storage

Disks:

LVM:

LVM-Thin:

Directory:

ZFS: empty

I'm having trouble getting vGPU's to work, so I will probably have to downgrade to PVE 7 anyways. Then I will have to format all in any case...

 

[carles89]

Well, I see you have two disks, one for boot and another one to use with your VMs. You should recreate the one that you want to use with your VMs using a snapshot-compatible storage.

1. Backup (if needed) and delete all your VMs.
2. Delete local-windows storage from Datacenter -> Storage
3. Destroy /mnt/pve/local-windows by selecting it and using More -> Destroy

4. Go to Disks and clean your 3,2TB disk by clicking on it, then "Wipe Disk" and then "Initialize Disk with GPT".

5. Now go to Disks and create a new pool. You can use LVM-thin or ZFS, depending on your needs. ZFS is safer and allows you to add a second disk later to build a mirror, but it needs more RAM (with ECC) and enterprise SSDs are preferred[1].

After you've created your new pool, recreate/restore your VMs and make sure all its disks are on the new pool.

I'm having trouble getting vGPU's to work, so I will probably have to downgrade to PVE 7 anyways. Then I will have to format all in any case...

If you have to reinstall, you'll have to do the same steps I provided, since the secondary disk will not be automatically configured by the installer. Also take into account PVE7 is EOL since 2024-07.

[1] https://pve.proxmox.com/wiki/ZFS_on_Linux#_hardware