some filesystems support snapshots for directories. your software does not have to have "compatibility" for it, it just works. with BTRFS you can even mount/wo

some filesystems support snapshots for directories. your software does not have to have "compatibility" for it, it just works. with BTRFS you can even mount/work with multiple snapshots of same directory at once. it is great for debugging. deduplication will save you space.