Image Format Specification

An image file: image.tar.zst is an zstd compressed tar-ball containing the following files:

• disk.img, raw disk image (as sparse file).
• layer.qcow2, qcow2 file with disk.img as backing file.
• machine.json, JSON definition of machine configuration.

When constructing the tar-ball it's important to use GNU tar with the -S option to ensure sparse file support.