When we use vmexport download raw format - downloaded disk image file is of the size of PVC. Example: cirros image is about 13-17 Mi, but downloaded raw image is 1 Gi

4.15 (may be in other verison as well)

Always. Both on HPP FS storage, and on OCS Block

1. Create a DV

apiVersion: cdi.kubevirt.io/v1beta1
kind: DataVolume
metadata:
  name: dv-source-hpp
  annotations:
    cdi.kubevirt.io/storage.bind.immediate.requested: 'true'
spec:
  source:
      http:
         url: <cirros-0.4.0-x86_64-disk.qcow2>
  storage:
    resources:
      requests:
        storage: 1Gi
    storageClassName: hostpath-csi-basic

2. Download disk.img.gz

$ virtctl vmexport download vm-export-pvc-hpp --pvc=dv-source-hpp --output=disk.img.gz
Downloading file: 12.64 MiB [==>________________] 3.12 MiB p/s
Download finished succesfully
VirtualMachineExport 'default/vm-export-pvc-hpp' deleted succesfully 

3. Download disk image in raw format

$ virtctl vmexport download vm-export-pvc-hpp --pvc=dv-source-hpp --output=disk-raw.img --format=raw
VirtualMachineExport 'default/vm-export-pvc-hpp' created succesfully
Decompressing image:
Downloading file: 12.64 MiB [___________________] 3.17 MiB p/s             
Download finished succesfully
VirtualMachineExport 'default/vm-export-pvc-hpp' deleted succesfully

4. Look at the file size difference:

$ ll
total 1061528
-rw-rw-r--. 1 cloud-user cloud-user   13255182 Dec 11 10:03 disk.img.gz
-rw-rw-r--. 1 cloud-user cloud-user 1073741824 Dec 11 10:04 disk-raw.img

5. Run the qemu-img info on both images:

$ qemu-img info disk.img.gz
image: disk.img.gz
file format: raw
virtual size: 12.6 MiB (13255680 bytes)
disk size: 12.6 MiB

$ qemu-img info disk-raw.img
image: disk-raw.img
file format: raw
virtual size: 1 GiB (1073741824 bytes)
disk size: 1 GiB

raw image is 1 GiB (like the PVC size)

raw image should be around 13-17 MiB