virt-sparsify

Create compressed sparse image

$ virt-sparsify --compress [path/to/image.qcow2] [path/to/new_image.qcow2]

$ virt-sparsify --in-place [path/to/image.img]

$ virt-sparsify [path/to/image] --convert [qcow2|raw|vdi] [path/to/new_image]

virt-sparsify [OPTIONS] INPUT OUTPUT

virt-sparsify makes virtual machine disk images thin-provisioned by removing unused space and creating sparse files. This can significantly reduce disk image file sizes.
The tool reclaims space by zeroing free blocks within the guest filesystem and then creating a sparse copy.

--compress

Compress output file

Sparsify image in-place

Convert to specified format (qcow2, raw, vdi, etc.)

Only use on offline virtual machines to avoid data corruption. Requires sufficient disk space for output image. Original image should be backed up before in-place operation.

virt-resize(1), qemu-img(1)