virt-sparsify –inplace

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/virtualization_deployment_and_administration_guide/virt-sparsify

Use to make a qcow2 disk remove empty space

Make sure the guest is compatible, and shutdown, if the disk is for a vm. Windows should be by default.

Check with this command, in cmd or PowerShell:

from https://pve.proxmox.com/wiki/Shrink_Qcow2_Disk_Files#Windows_Guest_Preparation

fsutil behavior query DisableDeleteNotify

# and this to change if it's not set to 0.

fsutil behavior set DisableDeleteNotify 0

in the host

#> virt-sparsify --in-place disk.qcow2

The above example is a disk formatted with ntfs/fat etc..

Other helpful info, verifying the sparse sizes.

#> du -h <file>
#> du -h  --apparent-size <file>

# https://wiki.archlinux.org/title/Sparse_file