OpenZFS on OS X

I just found the .log and .err file

The .log file was a bit terse and it seems like it stemmed from the action: lines when there is a problem.

The .err file only logged stuff at boot time. There was a lot on zed in /var/log/system.log that was not seen in openzfsonosx.*

But the major thing was that it lacked timestamps. I have no clue when the stuff happened. Was it an old problem? A recent?

Those logs do nothing more or less than capture the "stdout" (standard out, file descriptor 1) and "stderr" (standard error, file descriptor 2) from the running of the launchd job.