[SOLVED] Backup Windows VM with VirtIO HDD

[MH_MUC]

Hi everyone.
I am using Proxmox for Linux CTs primarily. I just setup the first Windows VM with VirtIO according best practices guide.
I noticed that I can't choose qcow2-Image format. I guess that is because I am using ZFS on the host.

The windows-host has a 100GB disk with 20 GB used. When I start a snapshot backup it seems to backup 100 GB, that use up 100 GB on our backup storage.
Is there a lighter solution to just backup used space?

Thank you very much!

EDIT: Alright I guess the backup takes longer as the whole volume is somehow parsed, but the resulting archive is as small as the true used diskspace in the VM.

 

[Stefan_R]

Seems you have solved the question yourself, but just to clarify: Yes, we need to check the entire disk for VMA backups, since we don't know which parts are allocated or have been changed by the VM. In the output however, zero chunks will be compressed down efficiently.

In case you need faster backups, if you use our Backup Server you can take truly incremental backups (currently only as long as the VM is not shut down), which will complete much faster as they only need to check modified blocks.