[SOLVED] [LVM Storage][Snapshots] Proxmox 9 Snapshot for LVM backed drive

[hac3ru]

Hello,

I have updated to Proxmox 9 not long ago and I was really excited to test out the snapshot feature available with LVM and LVM-Thin backed storage. The problem is..... it's not really working.
The scenario:
I have a Proxmox node (running 9.0.10) with two LVM storages:

lvm: LOCAL_VOL4TB
        vgname LOCAL_VOL4TB
        content rootdir,images
        nodes ZRH-GWL-TTA001-CS01
        shared 0

lvm: LOCAL_VOL16TB
        vgname LOCAL_VOL16TB
        content rootdir,images
        nodes ZRH-GWL-TTA001-CS01
        shared 0

I have created a dummy machine on one of the storages. VM's config:

boot: order=scsi0;ide2;net0
cores: 1
cpu: x86-64-v2-AES
ide2: none,media=cdrom
memory: 2048
meta: creation-qemu=10.0.2,ctime=1758185438
name: Test-Snapshot
net0: virtio=BC:24:11:9F:6E:0F,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: LOCAL_VOL16TB:vm-102-disk-0,iothread=1,size=32G
scsihw: virtio-scsi-single
smbios1: uuid=330380b1-c3e1-4dde-8bbe-79608063a86b
sockets: 1
vmgenid: ff913763-1e55-4c97-a07f-a930b6e6f10c

I was under the impression that I can snapshot this machine, as it uses an LVM storage. When I go under VM -> Snapshots -> I'm greeted by The current guest configuration does not support taking new snapshots
What am I doing wrong?

Thanks in advance!

 

[hac3ru]

For everyone having the same issue, RTFM

You need to enable the Allow Snapshots as Volume-Chain under Datacenter -> Storage -> your storage.
Once that's done, you need to migrate the Disk of the VM and set it as qcow2. You will have the option to migrate the disk to the storage of your choice as qcow2.

I was under the impression that you can take snapshots of RAW disks, I didn't know that it must be a qcow2 and that support for qcow2 was added for storages. The documentation is rather confusing - at least to me.

 

[tokin]

Hi,

There should be "snapshot-as-volume-chain 1 " for the LVM in storage.cfg.
Example:

lvm: LOCAL_VOL4TB
        vgname LOCAL_VOL4TB
        content rootdir,images
        nodes ZRH-GWL-TTA001-CS01
        shared 0
        snapshot-as-volume-chain 1  <<<<<<<<<<<<<<<<<<

 

[_John_Doe]

For everyone having the same issue, RTFM

You need to enable the Allow Snapshots as Volume-Chain under Datacenter -> Storage -> your storage.
Once that's done, you need to migrate the Disk of the VM and set it as qcow2. You will have the option to migrate the disk to the storage of your choice as qcow2.

I was under the impression that you can take snapshots of RAW disks, I didn't know that it must be a qcow2 and that support for qcow2 was added for storages. The documentation is rather confusing - at least to me.

It still doesn't work for me. I have LVM on top of FC-based storage, I have the Shared option enabled, and I have the Allow Snapshots as Volume-Chain option enabled. I create a new VM with a qcow2 disk, install the system, install VirtIO drivers, install QEMU Guest Agent, and still get the message “The current guest configuration does not support taking new snapshots.”
PVE 9.0.3.

EDIT:
OK, I found the cause. The problem is TPM. When a VM has TPM, the snapshot option is not active. When TPM is removed from the same VM, the snapshot option immediately becomes available.