Re: finding cause of reboot

On Fri, Oct 17, 2025, 2:12 PM mike tancsa <mike@sentex.net> wrote:

> On 10/17/2025 12:16 PM, void wrote:
> > On Fri, Oct 17, 2025 at 09:56:29AM -0400, mike tancsa wrote:
> >> Not sure if it helps in this case or not, but If you capture smartctl
> >> info regularly, you can some times infer from the disk power cycle
> >> count and power on hours if the box rebooted due to a power issue or
> >> not.
> >
> > Good point.
> >
> > I'm unsure how I'd distinguish between soft power cycle
> > and reboot though. The latter i'd expect to increment power cycle
> > count the former might but it might not.
>
> In my case, I had it with a failing power supply or one that could not
> deal with load.  In my case showed power cycle counts increasing.  Where
> as, a shutdown -r now before
>
> 0{r-14mfitest}# smartctl -a /dev/ada0 | grep -i power
>                                          entering power-saving mode.
>    9 Power_On_Hours          0x0032   100   100   000    Old_age
>   Always       -       40206
>   12 Power_Cycle_Count       0x0032   100   100   000    Old_age
>   Always       -       91
> 0{r-14mfitest}#
>
> and after a reboot
>
> s0{r-14mfitest}# smartctl -a /dev/ada0 | grep -i power
>                                          entering power-saving mode.
>    9 Power_On_Hours          0x0032   100   100   000    Old_age
>   Always       -       40206
>   12 Power_Cycle_Count       0x0032   100   100   000    Old_age
>   Always       -       91
> 0{r-14mfitest}#
>
> At least on my SuperMicro board shows the same power cycle count.   Like
> you said, probably does not apply in your case, but sometimes handy to
> keep in the back pocket
>

You can also look at the unclean shutdown count in nvme drives...

nvmecontrol logpage -p2 nvme0

to catch power issues.

Warner

     ---Mike
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