Scott Silverman wrote:
> In the past I've found that the console may have blanked (due to time)
> and when the system locked up/hung it won't unblank. Booting with
> "consoleblank=0" on the kernel command line will ensure that whatever is
> printed to the console (oops, panic, etc) will be there for you to see
> when you connect.
>
> I've had intermittent success in that type of situation with the SysRq
> key(s), see https://en.wikipedia.org/wiki/Magic_SysRq_key . They do
> require that you have it configured/enabled ahead of time. If you access
> the console over a BMC/IPMI KVM session it can be very difficult, if not
> impossible, to enter the keystroke as well.
>
Hmmm... thanks. I'm sure I've heard about the magic sysreq, but had
forgotten, never used it. I'll try that if this happens again.
mark
> Good luck,
> Scott
>
>
>
>
>
>
> On Wed, May 22, 2019 at 8:46 AM Stephen John Smoogen <smooge@xxxxxxxxx>
> wrote:
>
>
>> On Wed, 22 May 2019 at 09:30, mark <m.roth@xxxxxxxxx> wrote:
>>
>>
>>> Ok, we used to get this occasionally on cluster nodes, and we just
>>> got it on a fileserver (very bad). The system is discovered to be
>>> unresponsive:
>>> it doesn't ping, and plugging a console in, you can see that it's not
>>> dead, but there nothing at all on the screen, nor does it respond to
>>> even <ctrl-alt-del>. The only answer is to power cycle it; it comes up
>>> fine.
>>>
>>> Nothing in /var/log/dmesg or /var/log/messages. No abrts I can find.
>>> sar tells me it went unredponsive between 18:10 and 10:20 yesterday.
>>> Note
>>>
>> that
>>> there are no further entries in sar, either, for yesterday, after the
>>> event, and nothing till I power cycled it.
>>>
>>>
>> From the above description, I would normally say it sounds like
>> hardware. However, why do you say the system is not dead when you plug
>> in a console.. but there is nothing on the screen and it doesn't respond
>> to control-alt-delete. To me that sounds like 'dead'. Usually the cpu is
>> hardlocked or the hardware went into 'over-heat' and put everything in
>> a deep sleep hoping it would cool down but never wake up.
>>
>>
>>
>>> Has anyone else seen this - I can't imagine it's only us - or have
>>> any thoughts?
>>>
>>> C 7, 7.6.1810
>>>
>>>
>>> mark
>>>
>>>
>>> _______________________________________________
>>> CentOS mailing list
>>> CentOS@xxxxxxxxxx
>>> https://lists.centos.org/mailman/listinfo/centos
>>>
>>>
>>
>>
>> --
>> Stephen J Smoogen.
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>>
>>
>
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