I must have missed something in the two pages of troubleshooting but just in case I didn't...
Did anyone go into the Boot Environment and Activate the previous version and reboot. You know, the version you were running before all hell broke loose? This will validate if it actually was the update to TrueNAS 13.0. So long as you did not upgrade the pool feature set, you may be able to roll back. If you updated the feature set, you are likely stuck with version 13.0 for now.
I think it's time to rule out items vice trying to go directly to a component.
What is your boot device and where is your System Dataset stored? This may not have anything to do with your problem but it's data that might help us figure out what is going on.
Lets hit on the drives for a minute, are SMART tests being conducted on them? Have you checked to see when the last Long/Extended test passed on each drive? TrueNAS should report a failure but if you are not testing, that is a problem, even if not related, but it can rule it out as a possible problem.
I have a few other things to do as well but it will take me some time to type up. I really should make a guide on this since there are basic things everyone can do to isolate a problem. I hope you are able to roll back to TrueNAS 12.x and if that fixes it, then we can discuss how to test if TrueNAS 13.0 is the problem or maybe the upgrade went poorly.
I would actually like to see the output for each drive [in code brackets] using this command
Code:
smartctl -x /dev/ada0
(repeat for each drive) and I do want the entire output, some people trim it thinking they are being helpful when in reality they remove something important. If it makes it easier for you (and it will) run this command
Code:
smartctl -x /dev/ada0 >> testfile.txt
and then rerun the command for each drive. All the data will be in the file testfile.txt. Make sure you run this command form a location you can grab a copy of this file, like a shared dataset. Then you can just attach the text file to a posting. Easy.