"Disk move" results in non sparse qcow2 disk clone

[Joel LaCalamita]

Using "Disk move" via the GUI to migrate disks to a replacement storage array. The resultant "new" qcow disk are seemingly not sparse. I tried it with the VM running and with VM stopped. I saw in a post from 2020 result may be different if VM was shutdown.

I used both du and qemu-img info to check actual space util.

I'm still running PVE 6.X in this cluster if it makes a difference.

If all my qcow become non sparse the replacement array will not have enough capacity.

I'm not having luck finding and answer in prior forum.

I'd appreciate and advice or guidance.

image: ..../images/101/vm-101-disk-1.qcow2
file format: qcow2
virtual size: 60 GiB (64424509440 bytes)
disk size: 17.4 GiB
cluster_size: 65536
Format specific information:
compat: 1.1
compression type: zlib
lazy refcounts: false
refcount bits: 16
corrupt: false
extended l2: false
image: .../101/vm-101-disk-1.qcow2
file format: qcow2
virtual size: 60 GiB (64424509440 bytes)
disk size: 59.1 GiB
cluster_size: 65536
Format specific information:
compat: 1.1
compression type: zlib
lazy refcounts: false
refcount bits: 16
corrupt: false
extended l2: false

 

[Joel LaCalamita]

I did a bit more testing, created a new 5GB disk, shutdown VM, then performed a move disk, resultant disk is now sparse but not quite as sparse as the original, just a few 100 kb LARGER, about 2.5x the size.

virtual size: 5 GiB (5368709120 bytes)
disk size: 394 KiB
-versus-
virtual size: 5 GiB (5368709120 bytes)
disk size: 968 KiB

Tested move with another with two VM/qcow while VMs were down. Sparse but ~2.5 times larger than original in both cases.

virtual size: 32 GiB (34359738368 bytes)
disk size: 4.41 GiB
-versus-
virtual size: 32 GiB (34359738368 bytes)
disk size: 11.6 GiB

virtual size: 32 GiB (34359738368 bytes)
disk size: 4.32 GiB
-versus-
virtual size: 32 GiB (34359738368 bytes)
disk size: 11.1 GiB