I don’t know how BTRON did it, but you could definitely do revision history with copy-on-write.
I recall Apple having ideas about a filesystem that didn’t have filenames, but instead had keywords that described the files. I looked for it but the only thing I could find was the unreleased object oriented filesystem demoed in 1994 with Copland, but I could’ve sworn they had something similar but more recent.
I don’t know how BTRON did it, but you could definitely do revision history with copy-on-write.
I recall Apple having ideas about a filesystem that didn’t have filenames, but instead had keywords that described the files. I looked for it but the only thing I could find was the unreleased object oriented filesystem demoed in 1994 with Copland, but I could’ve sworn they had something similar but more recent.