Thin provision shows differently between new disk and moved disk


New Member
Sep 26, 2021
I got a 256GB NVME and built a Windows Server VM on a local ZFS with 8TB thin provisioned disks.

I then shared it as an SMB/CIFS volume and registered it as PVE storage, to have a VM running on it. The disk contains Windows 11 OS. I then tried several restores and disk moves between Local-ZFS and the SMB volume.

According to the QCOW2 virtual drive file size on Windows Server, it consumes more than 268 GB. This clearly exceeds the size of the physical disk. In contrast, PVE says it's consuming only about 50 GB, which is equivalent to the size of Win11 OS.

What I don't understand is that if I choose SMB/CIFS volume as the disk location from the beginning and create a VM, the "actual size" is displayed as thin provisioned. The actual size is smaller, as you may see on 1st attached picture.

But, if you move or restore from Local-ZFS to SMB/CIFS volume, the "actual size" is same as disk size and you will not see the thin provisioning in action, as you see on 2nd attached picture. On PVE again, it seems that the thin provision is working. This is what is confusing me.

As the simplest way, should I create VM on SMB/CIFS volume and not try to move/restore from local-ZFS? Any advice will be welcome. Thank you.


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