Create a raw image file that can be checked and debugged using filesystem utilities such as e2fsck or debugfs. Raw images are created as sparse files. Either compress the image file before moving it, or use the --sparse=always option when copying it with cp.

Handle files that have "holes" (are defined as a certain size, but have less data). always creates a sparse file, auto creates one if the input file is sparse, and never creates a non-sparse file without holes.