jansucan / diff-dd Goto Github PK

Add an option to force overwriting without asking.

C is making it too laborious to apply good software engineering practices when the amount of code increases.

Currently, diff-dd can create only a differential backup, i.e., a backup which contains data changed since the last full backup.

Hi, my use-case is not what you intended, but I think diff-dd could be used for my scenario. I am doing some experiments, but I thought you may have knowledge about my situation that you could possibly share.

I have a small linux system I am building up using docker. It is alpine linux, and the output of my build is a disk image. The system uses a read-only root and bind mounts / overlayfs to allow writes where necessary. I am looking to provide image based updates, which is trivial (wget -O - ... | dd of=/dev/sda3). But I would like to provide deltas if possible.

I currently build each image from scratch, by installing packages into a chroot and then bind mounting a file (formatted ext4) and copying the chroot into it. The diffs are basically 100% different. I plan to provide deltas for each version against the previous two versions. If a larger upgrade is necessary, it will just use the full image.

In your development and planning for this project, did you come across anything that might help me to keep the images "consistent" across builds? Is there a better filesystem (that allocates files in a predictable / consistent way). Should I base an image off the previous image and rsync the chroot into it? Can I copy files in a specific order to maintain consistency? fsck, defrag or anything that can help to arrange data blocks?

If you don't have any information that can help me, that is fine, thank you for your time. Anything you can provide is helpful. I am researching now and doing some tests on my own.

Thanks.

Currently, the operation (backup, restore) is selected based on the number of arguments, which can be confusing.

Proposed command line interface:

diff-dd backup [-s SECTOR_SIZE] [-b BUFFER_SIZE] INFILE REFFILE BACKUPFILE
diff-dd restore [-s SECTOR_SIZE] [-b BUFFER_SIZE] BACKUPFILE OUTFILE