Sure but that alone doesn't mean it's any less suitable on Ubuntu. I'm just trying to understand what the differences are in implementation, reliability, etc.
ZFS on FreeBSD and on Illumos has been used, abused, tested and stressed all the way to the Moon and beyond. Loads of people with loads of data over loads time.
This makes bugs appear, and get addressed, and eventually gives you confidence that nothing nasty remains uncorrected, and it won't eat your data.
ZFS on Linux, due to the unfortunate licensing situation, is considerably less tested and thus scary, data-eating bugs are at least a bit more likely to exist.
> On the other hand Linux is far more popular so I wouldn't be surprised if ZFS on Linux already clocks more hours of usage than on BSD.
Yes and no. Few people, even among the Linux crowd, are aware it exists or feel like trusting it with important data sets/jobs. Those few are the most likely to be equally at ease running FreeBSD or Illumos (or Solaris), where the damn thing is known to work really well.
ZFS-on-Linux has not been mainstream (or existed) for as long as ZFS has been integrated inside FreeBSD. illumos is the free software fork of OpenSolaris -- so it's the repo of record for modern ZFS development.
ZoL uses an emulation layer to make Linux look more like something with Unix ancestry, ancestry that BSD and Solaris share. The biggest difference I believe is in memory management / fs cache integration.
In practice this means that ZoL may require more memory to be stable, or may be less stable depending on configuration if low in memory.
I've run ZFS on Solaris (by way of Nexenta) and Linux since 2008 or so. I haven't seen much reliability difference in practice. I've had fewer hiccups streaming video from Linux though.
