In my case illumos provided two things: - zones allowed for a much higher deployment density and better utilisation of our hardware than other virtualization t

In my case illumos provided two things: - zones allowed for a much higher deployment density and better utilisation of our hardware than other virtualization technology would have. - zfs snapshots. We've integrated those into our product and when a customer messes up they now have button to instantly restore to a known good state. Doing both of these things would have been a lot harder on another os.