Hello, first of all, I want to say that I uploaded a very big syslog file because I think it's better to give more than needed, if that's okay.

2 days ago (04.11.2025), I started to replace a 6 TB disk of my array with an 18 TB disk (parity is 18 TB as well). I also had the old one attached, but as an unassigned device and not mounted. The rebuild needed 1 day, but everything was fine. So I stopped the server again to put everything in place and get rid of the old disk (05.11.2025). I booted again, and everything was fine. Somehow, I think 5 hours after the start the server died out of nowhere. I couldn't see why in the logs. So I had to press the button on the case of my server and shut down the server, and started it again at probably 19:00 on 05.11.2025 (could also be a bit later). I wanted to go to sleep at approximately 00:30 on 06.11.2025, and the server again crashed, so I did the same.

The next morning, the server was offline again (after 5 hours already, but I slept). I rebooted, and my pools (named cache and safety) were empty. The array was there and worked, but I found the disks in unassigned devices and had to put them in the empty pools again because I rebooted several times and didn't see it first.

Additional information: my br0 network was gone after the disk replacement, and after some reboot, it was randomly back again, and it is gone again now. Has it also something to do with this or is it because of the crashs?

Do you have any idea what is going on?

syslog-192.168.178.29.log

Edited November 6, 2025Nov 6 by sasbro97

Unfortunately, there's nothing relevant logged, this typically mesan a hardware issue, post the full diagnostics mostly to see the hardware used.

@JorgeB I hope that helps. I know that one 4 TB disk started to have a smart error. First it was just with value 1 and now 4. But this already before the disk replacement and it's just a RAID 1 data disk, not even used for Docker.

unraid-server-diagnostics-20251106-1021.zip

Unlikely that a disk would cause this. Regarding the hardware, nothing jumps out as an obvious issue; it's a 13th-gen CPU, but it's not a K model, and typically those are not affected by the Intel 13/14 gen issue. Still, good to look for a BIOS update; it could help.

Another thing worth trying is because Memtest is only definitive if it finds errors, and since you have multiple RAM sticks, try using the server with just one pair, if the same try with the other one, that will basically rule out bad RAM.

@JorgeB I will try those things and come back if I have a question or if I find a solution. Thanks for the help!

Edited November 8, 2025Nov 8 by sasbro97

Hey @JorgeB ,

It fixed itself. It was very unlucky because the day I posted this, I had to go on a trip for 3 days very early in the morning, and I could only restart the server physically. I created a script that reboots the server every 4,5 hours and let it run until yesterday (so for 3 days). Then I deactivated the script to see if the problem still exists, and until now the server has been running for 1 day and 10 hours. If I remember it correctly, I swapped some hardware of the server a year ago and had the same problem that the server randomly crashed then.

I also never found out why. Did any other users report a similar behavior? I mean, it's weird because now everything is just like nothing happened. Even the br0 network came back.

38 minutes ago, sasbro97 said:

Did any other users report a similar behavior?

Not that I remember, and I would recommend waiting a few more days before considering it solved.

In the end, I have no idea. Everything works as it used to before...