On Wed, May 3, 2023 at 5:21 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > rsync --link-dest
I wonder if rsync will grow a mode that can use copy_file_range() to share blocks with a reference file (= previous backup). Something like --copy-range-dest. That'd work for large-file relations (assuming a file system that has block sharing, like XFS and ZFS). You wouldn't get the "mtime is enough, I don't even need to read the bytes" optimisation, which I assume makes all database hackers feel a bit queasy anyway, but you'd get the space savings via the usual rolling checksum or a cheaper version that only looks for strong checksum matches at the same offset, or whatever other tricks rsync might have up its sleeve.
