[ClusterLabs] 2-Node Cluster - fencing with just one node running ?

[Reid Wahl]

On Thursday, August 4, 2022, Lentes, Bernd <
bernd.lentes at helmholtz-muenchen.de> wrote:
> ----- On 4 Aug, 2022, at 19:46, Reid Wahl nwahl at redhat.com wrote:
>
>>> It shuts down ha-idg-2:
>>> 2022-08-03T01:19:51.866200+02:00 ha-idg-2 systemd-logind[1535]: Power
key
>>> pressed.
>>> 2022-08-03T01:19:52.048335+02:00 ha-idg-2 systemd-logind[1535]: System
is
>>> powering down.
>>> 2022-08-03T01:19:52.051815+02:00 ha-idg-2 systemd[1]: Stopped target
>>> resource-agents dependencies.
>>>  ...
>>
>> Yes, but it thought it was shutting down ha-idg-1.
>>
>>>
>>> Then it stops cluster software on ha-idg-1:
>>> Aug 03 01:19:58 [19361] ha-idg-1 pacemakerd:  warning: pcmk_child_exit:
Shutting
>>> cluster down because crmd[19368] had fatal failure
>>> Aug 03 01:19:58 [19361] ha-idg-1 pacemakerd:   notice:
pcmk_shutdown_worker:
>>> Shutting down Pacemaker
>>> Aug 03 01:19:58 [19361] ha-idg-1 pacemakerd:   notice: stop_child:
Stopping
>>> pengine | sent signal 15 to process 19367
>>>  ...
>>
>> Node ha-idg-1 received a notification from the fencer that said "hey,
>> we just fenced ha-idg-1!" Then it said "oh no, that's me! I'll shut
>> myself down now."
>>
>> That can be helpful if we're using fabric fencing. That's not supposed
>> to happen with power fencing. The shutdown on ha-idg-1 didn't hurt
>> anything, but it should have gotten powered off (instead of powering
>> off ha-idg-2.
>>
> What is "fabric" fencing and "power" fencing ?
> Fabric something like ILO or IPMI ? And power fencing is cutting off
power by controllable
> UPS or power switches ?

Fabric fencing is cutting off access to storage or the network. Power
fencing is cutting off power, whether via iLO or UPS or whatever.
>
> Bernd

-- 
Regards,

Reid Wahl (He/Him)
Senior Software Engineer, Red Hat
RHEL High Availability - Pacemaker
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