This morning i woke to an email alert that my offsite backup TrueNAS server had had an unexpected restart. I've checked the report graphs for the UPS state but it doesn't appear to have been a power issue, I then noticed the following alarm...
Failed to check for alert VolumeStatus: Traceback (most recent call last): File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/alert.py", line 706, in __run_source alerts = (await alert_source.check()) or  File "/usr/local/lib/python3.8/site-packages/middlewared/alert/source/volume_status.py", line 31, in check for vdev in await self.middleware.call("pool.flatten_topology", pool["topology"]): File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1238, in call return await self._call( File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1206, in _call return await self.run_in_executor(prepared_call.executor, methodobj, *prepared_call.args) File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1110, in run_in_executor return await loop.run_in_executor(pool, functools.partial(method, *args, **kwargs)) File "/usr/local/lib/python3.8/site-packages/middlewared/utils/io_thread_pool_executor.py", line 25, in run result = self.fn(*self.args, **self.kwargs) File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool.py", line 438, in flatten_topology d = deque(sum(topology.values(), )) AttributeError: 'NoneType' object has no attribute 'values'
2021-01-24 07:23:41 (Europe/London)
The server reports that its uptime is 2:09 as of 09:32, which puts the restart at roughly the same time. I'm running the lastest 12.0-U1.1
Server has 8x 8Tb WD Reds (Pre SMR-gate)
2x SanDisk 256Gb SSDs (for VMs) Mirroed
2x Integral SSDs mirrored as boot drives.
256Gb ECC memory.
2x LSI 9217-8I in IT Mode
The server sites idle throughout the day, and recieved replicated snapshots over a 200Mbps link from my primary server overnight, however these jobs are on hold as I'm rebuilding my primary site, so the server shouldn't have been doing anything.
Please let me know if theres any logs/details I can pull to assist with troubleshooting or if theres any information you need that I'm missed.
Thank you very much for your assistance in advance.