There was a point a few years ago where Sun could have had the
  next generation UNIX filesystem. It was in Solaris (and people
  were excited), there was a port to MacOS X (that was quite
  exciting for people) and there was a couple of ways to run it on
  linux (and people were excited). So… instead of the fractured
  landscape of ext3, HFS+ and (the various variations of) UFS we
  could have had one file system that was common between all of the
  commonly used UNIX-like variants. Think of being able to use a
  file system on a removable drive that isn’t FAT and being able to
  take it from machine to machine (well… Windows would be a
  problem, but it always is).
  There was some really great work done in OpenSolaris with
  integration between the file manager and ZFS snapshots (a slider
  bar to browse the history of a directory, an idea I’ve championed
  for over a decade now, although the Sun implementation was likely
  completely independently developed). …
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