I'm trying to streamline a backup system using ZFS. In our situation, we're writing pg_dump files repeatedly, each file being highly similar to the previous file. Is there a file system (EG: ext4? xfs?) that, when re-writing a similar file, will write only the changed blocks and not rewrite the entire file to a new set of blocks? Assume that we're writing a 500 MB file with only 100 KB of changes. Other than a utility like diff, is there a file system that would only write 100KB and not 500 MB of data? In concept, this would work similarly to using the 'diff' utility... -Ben