TrueNAS version: 25.10.3.1 - Goldeye
I just migrated back to TrueNAS from Unraid, so forgive me if it’s a bit of a noob post.
I experienced a reboot I did not tell the server to do. I’m trying to figure out what caused it, but I don’t see a way to look at the system log. Can anyone point me in the right direction?
This isn’t really a TrueNAS question as much as it is a hardware issue. You are basically experiencing a system instability due to a hardware problem that can range from bad PSU, bad RAM, to poor airflow and other issues.
TrueNAS does not generally restart itself which is why you have a response to check for hardware issues.
You can look for log files here /var/log and take a look at those. I won’t tell you that you will easily find the smoking gun, not unless you know exactly when this the reboot occurred.
As for system stability, it is easy to run a few stability tests. Also, do you have enough RAM to do whatever you are doing? Is your system on an UPS?
If you find the problems happens with some frequency, if you have a few apps, then disable them to see if this stops the reboot issue.
Good Luck, hope the issue either no longer happens or you quickly identify the issue.
I was able to get some help with accessing the logs, and was able to trace it back to an app that wasn’t working properly. may not have given it enough RAM, still not sure. I removed it and that solved the issue. System has been stable since, and is working just fine. Appreciate the responses.
Hardware details could help. How long was system online for? What apps do you have? Vms? Is truenas run on bare metal or virtualized?
Edit: obviously I reply after you fixed the issue, congratz 
If this is true, that sounds like a terrible bug or I may even say a security vulnerability. An app should not be rebooting your machine even if it is not working properly. It kind of violates that whole “sandbox” paradigm if it can affect the host machine that easily.
OOM is OOM imo, not necessarily a security issue. Terrible bug & memory leak? Very possible. But I notice Scale doesn’t release ram from ARC as cleanly as Core did, so I could see it happen. Especially if there is an iGPU taking up a few gigs of ram.
I mean, OOM and getting your app killed is one thing, this is a reboot of the physical machine, which is a completely different thing. An app should not be able to reboot the physical machine just because it ran into OOM conditions. I see that as a security issue.
I’m not sure how Linux is supposed to behave in OOM conditions, but neither Windows nor FreeBSD does this; though I have heard from others that Linux, though it has reputation for being excellent on low-end machines, is absolutely horrendous when it does run out of memory and the OOM killer often goes berserk.
oddly enough .. I was experiencing random reboots after having an uptime of 40 something days running just Plex and some SMB shares
I recently installed Adguard Home and I’m assumnig it is the culprit .. or the added load on the system is exposing some hardware instabilities
Today there was an update for Adguard .. and I updated my motherboards BIOS to the latest version that recently became available .. I did some tweaks involving PBO as well .. I guess time will tell if everything is stable again
