This weekend I took an old Mac mini that had been running FreeBSD in a virtual machine and managing a ZFS pool, and "upgraded" it to El Cap, got rid of the virtual machine, and installed OpenZFS & imported the pool. All the data is there, and performance is way higher.
Sadly every time I attempt to scrub the pool the system hangs (I've left it alone for a half hour to see if it recovers). I don't see anything interesting in the logs. Am I missing a way to force a remote stack dump, or even to increase the logging verbosity? Or is this a known El Cap issue, and upgrading to something newer is better? (this system doesn't have other responsibilities, so I can upgrade it to whatever the hardware supports without getting in the way of anything else)
I don't actually have the Mac mini connected to a display, keyboard, or mouse. I can vnc in, and I can ssh in. I _can_ attach it to a display and such, but that would change it from something I can poke at one evening, to something that has to be scheduled significantly in advance...