Ubuntu 20.04 sudden crash while processing, how to know why?

[Colin Law]

On Sat, 13 Mar 2021, 07:03 Bo Berglund, <bo.berglund at gmail.com> wrote:

> I have a HP 8440w workstation running Ubuntu 20.04 LTS since an upgrade
> from
> 18.04 about a month ago. It is headless (no monitor attached) and when I
> need
> the GUI I use VNC from Windows 10.
>
> It runs scheduled at tasks to download hourly from a video stream using
> ffmpeg
> and this has worked fine for several weeks.
>
> The download task captures the stream for one hour into ts type files.
>
> Now while the at command was running I started a command line execution of
> another ffmpeg command to convert the format of an already downloaded ts
> file
> into mp4 and with a smaller video size (from 1280x720 to 852x480).
> So it rescales the video and converts into mp4 format.
>
> This command is contained inside a script which was started using the time
> function like this:
> time convertvideosize 480 input.ts output.mp4
>
> About a minute into the conversion the computer fan started up at higher
> speed
> and then suddenly the computer crashed.
>
> I started it again and looked at the /var/log/syslog file to see what
> happened
> but I did not find anything I could use.
> These are the 3 log lines before the crash:
>
> Mar 13 07:10:01 polaris-ubuntu systemd-resolved[554]: message repeated 14
> times:
> [ Server returned error NXDOMAIN, mitigating potential DNS violation
> DVE-2018-0001, retrying transaction with reduced feature level UDP.]
> Mar 13 07:10:01 polaris-ubuntu CRON[104176]: (bosse) CMD
> (/home/bosse/bin/logactivity)
> Mar 13 07:10:01 polaris-ubuntu systemd-resolved[554]: Server returned error
> NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying
> transaction
> with reduced feature level UDP.
>
> Then follows a line with about 600 NUL chars (0x00)
>


The DNS warning is nothing to worry about.  A log like that indicates a
sudden processor stop such as a power off or a hardware problem.  I would
be considering such issues as the power supply, system overheating, a
connector that needs reseating or something along those lines.

Colin


> Next is this presumably from the restart I did:
>
> Mar 13 07:16:51 polaris-ubuntu systemd-modules-load[361]: Inserted module
> 'lp'
> Mar 13 07:16:51 polaris-ubuntu systemd-modules-load[361]: Inserted module
> 'ppdev'
> Mar 13 07:16:51 polaris-ubuntu kernel: [    0.000000] microcode: microcode
> updated early to revision 0xa, date = 2018-05-08
>
> The last modified time of the output.mp4 file is 2021-03-13 07:15:02, so
> that is
> probably when the crash occurred.
> This shows that the syslog has not been written to close to the crash
> event.
>
> QUESTIONS:
> Is there any way I can find out what happened that caused the crash?
>
> And is there any Ubuntu tool to monitor the computer activity like Task
> Manager
> on Windows, for example to see the CPU load and temperature?
>
>
> --
> Bo Berglund
> Developer in Sweden
>
>
> --
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