This leaves me with three questions:
- Why does the system keep freezing up like this?
- Given that nothing is being recorded in the logs, where can I look for information to help me answer (1)?
- Is there a known bug or issue that could answer (1) without requiring an answer to (2).
The system overview is as follows:
Memory: 7.5 GiB
Processor: Intel® Xeon(R) CPU E3-1225 v3 @ 3.20GHz × 4
Graphics: AMD® Turks
Base system: Debian GNU/Linux 9 (stretch) 64-bit
Disk: 571.8 GB
Three different operating systems share a one-terabyte drive that I admit is horribly partitioned: Windows, Debian, and Ubuntu. Debian and Ubuntu share the same home partition. I checked, and the system does seem to be actively using the swap allocation, even if it reads empty in gparted.
I read on the Debian Admin (I think) site that such freezes without log entries could indicate hardware problems, particularly with memory. Moreover, the way the problem has progressed with increasing frequency could indicate some piece of hardware is slowly failing: the first freeze was seemingly at random, and then initially very rare, eventually to at least once per day, and now twice already today---and without any constant factor I can account for. However, after the last freeze, I ran the "quick test" from the boot menu on my system (HP), and everything checked out fine.
I have a one-terabyte external drive connected via USB 2.0 as well. The first freeze happened while I was rapidly switching between video files on this external drive, but I was not actively using it when any of the subsequent freezes happened. I think I tried disconnecting it before, but I disconnected it after the second freeze just to check again. If the system does not freeze again over the next week or so, I suppose we could consider the mystery solved.
I manually upgraded Debian from 8 to 9 on this system, but (mostly) followed the instructions on the website and did not have any major problems. Moreover, the freezes did not begin immediately upon upgrading. Nonetheless, I think I did accidentally miss a step, and had to manually remove a bunch of outdated packages or something like that. Also, my system is not perfect in that I do have unnecessary packages installed, so I cannot rule out a software error. I would expect to see something in one of the logs, though, if this were the case.
The computer is a mini-tower and is located in my office. I leave it on when I am not here primarily so that I can be certain that any changes to my files while at home are propagated to this computer so that I do not need to rely on Dropbox as my only redundancy. (I have also been meaning to ask our IT person about setting up a SSH tunnel from home.) That said, I rarely subject the computer to particularly demanding tasks.
I would be grateful if anyone can help me resolve this problem. I searched the forums beforehand to make sure I was not cross-posting, and I apologize if I missed something. I will gladly provide any further information requested. Thank you!