Building delta and patch strategies

Diffs and patches can be used between minor changes in system images, which could dramatically reduce the size of image archives. Encrypted images will likely not benefit from patches. Container images already benefit from this technique, with layers comprising an entire image and deduplicated common layers being identified by checksum. It’s simple enough to generate a patch between two images:

diff -u oldimage.qcow newimage.qcow > 1-patch.diff

The patch should be much smaller than storing the entire new image if there are only minor changes and both images are not compressed or encrypted. Generating patches may be a helpful way to archive old images but is probably not practical for active golden images.