Backup sizes

[ChrisKirk]

Hi,

Very new to Proxmox, a lot more experience with ESXi and Hyper-V. I've installed Proxmox in a home lab environment and provisioned an instance of OpenMediaVault for file sharing services. I gave OMV a small 10GB boot disk, and a second 1.5TB disk for data. Having loaded the data disk with the files I want it to share, the total data on the disk is about 450GB.

I then connected an external USB drive to the Proxmox server for backup, set up a mount point for the drive, and set up a backup schedule. Before the first scheduled run of the backup I kicked one off manually.

My understanding is that VM disks in Proxmox are, by default, thin provisioned, therefore my expectation was that the initial backup of the OMV VM would amount to little more than 460GB, however the size of the backup appears to be 1.5TB, i.e. the full size of the OMV disk as though it is not thin provisioned. This will make backups unwieldy at best.

The VM disks are SCSI, I didn't see any option for thin or full provisioning, I assume I'm doing something wrong here, but I can't see what. Can anyone advise?

 

[Stefan_R]

Thin or thick provisioning depends on the underlying storage, not any settings on the VM. How are you making the backup? Are you using compression?

It would also help to post your VM and storage config ('/etc/pve/qemu-server/<vmid>.conf' and '/etc/pve/storage.cfg' respectively).

 

[Dunuin]

If you are using the buildin backup function (vzdump) then proxmox will just create a archive of the complete virtual disks, so it is 1.5TB. If you use zstd or lz4 for the compression it will remove the empty space and you should get something that is 450GB or below.
Vzdump can't do incremental backups so every time the full 1.5TB will be written again and again. That way creating the backup will take forever and you will run out of storage very fast (but backups should be kept for months because of ransomware and so on).
So you might want to take a look at the Proxmox Backup Server and run it inside a VM with "qm set" passthroughed disk or better on another server. It can do incremental backups so only the changes since the last backup need to be transfered and stored.