LVM Storage on SAN, new VM and Disk show data from a previous deleted system/disk

[talos]

Hi,

today created a new VM to evaluate AlmaLinux 10.1, when i try to boot it, it booted an old Ubuntu System that was deleted a few days ago. This is LVM on a FC SAN with Snapshots as Volume Chains enabled.

It makes kinda sense if lvm is allocating something in thick mode but does itself nothing with data in that range. I think this is dangerous depending on who has access to a VM, an auto provision VM may accidently boot from disk and not ISO because there is a valid signature and parition. Is this expected with storage on LVM?

I think this may have an affect on Backup, if there is a lot of old data. Last time i created a new VM and backed it up, that was quiete large an almost no Zeros.

I would like to see some feature to let Proxmox zero out the whole lvm range on VM creation to make sure there is no existing data.

Is this a bug or expected?

 

[talos]

Post in thread 'Proxmox + shared LVM'

Sep 16, 2025

My guess: only the node that “owns” the VM can write metadata, but not 100% sure.

Normally when using Shared LVM the LV for a particular VM is only active on the node which owns the VM. You should not see a "dev" link for that LVM.

From your output, you are using the new QCOW/LVM technology. Keep in mind that it still has Experimental status. You may have run into something worth properly reporting.

You may want to collect and provide (best to use text encoded with CODE tags or SPOILER) from each node:
lsblk
multipath -ll
pvs
vgs
lvs

Are there any interesting messages in the...

• bbgeek17

• 

From this post, it looks like this is a expected behaviour of LVM. I still like the idea to have some optional zero out feature on LV creation. VM based or Cluster wide for security.

 

[LnxBil]

I still like the idea to have some optional zero out feature on LV creation.

There is the option to wipe it on volume removal, as explained in the documentation.

 

[talos]

There is the option to wipe it on volume removal, as explained in the documentation.

Thanks your help, i enabled this feature on my lvm storage and deleted a bigger test vm, i was surprised how fast the zeroing out process is, i expected it to take some times but 512gb was done in around 15 sek. I recreated the VM and there where no remains of the old partition/data, a backup only read zeros from storage, so proxmox was successful zeroIng out the data.

Next time i create a new volume for a pv, i zero it out before doing a pvcreate, so there is no old data from my old volumes.

 

[LnxBil]

i was surprised how fast the zeroing out process is, i expected it to take some times but 512gb was done in around 15 sek.

Yes, depending on the used backend zeoring, it can be very fast. It can also be very slow, I have experienced both.

Next time i create a new volume for a pv, i zero it out before doing a pvcreate, so there is no old data from my old volumes.

You can try to create a volume with the full available storage and delete the volume afterwards. Now, it should be zeroed for all further new VMs. Best to do that for a new VM.