My system seems to crash from time to time. I still don’t know what causes it.
If I leave it untouched for a few hours, sometimes, it crashes.
To resume, I have to force a reboot by unplugging the power cable (not even pressing the power button for N seconds seems to work).
Then, it seems to work just fine (after displaying some error messages about lost or orphaned inodes at boot). Until, one day, it happens again. When? I never know. It seems to follow some strange and unpredictable pattern.
Where should I start investigating?
Not to be that guy but have you checked the system logs when this happens?
What system logs do you think I should look first, and what should I be looking for?
Any expression I could grep?
I would check system level logs to start like dmesg and syslog.
Someone else might have better tips of what to grep for in the logs. One thing you could do is try to ssh into the system when it’s locked up and check the logs to see what’s being reported during or immediately before the lockup.
Once you get a sense for what’s going on at a system level you can start to look in more specific logs.