Comment Re:File versioning and backup flags (Score 1) 484
DragonFlyBSD's HAMMERFS does much of this - you can examine the version history of files and directories using hammer history and undo commands, and reference versions directly by appending @@ to filenames.
You can control how long history is preserved for and in what level of detail, as well as efficiently replicate it all across the network to remote filesystems (which can have their own, different rules). All this in addition to the more traditional named snapshots approach you're limited to with, e.g. ZFS.