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.
> 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.
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.