Hi, in the function __convert_image_to_qcow2 in src/debian_cloud_images/images/__init__.py we convert a raw image to qcow2 and use compression by adding -c. Since qemu 5.1 it support using zstd compression by adding -o compression_type=zstd to the qemu-img convert call. This is much faster than the default zlib compression algorithm and compresses a little bit smaller. Is it worth to switch? -- regards Thomas