[ClusterLabs Developers] How to implement fencing agent with no associated hardware device with Pacemaker?

Digimer lists at alteeve.ca
Wed Aug 5 00:25:30 EDT 2020

You'll need an agent that complies with the FenceAgentAPI. All pacemaker
cares about, fundamentally, is the agent's exit code (save for the
meta-data call it uses to know what is a valid config). It's entirely up
to you when you decide that a fence action has succeeded or failed.

Of course, reporting success without actually fencing the target could
end disastrously, so do your due diligence.



On 2020-08-04 4:57 p.m., Philippe M Stedman wrote:
> Hi Andrei,
> What if we had no hardware device and all we wanted to do was run a
> single command when fencing off a failed node. Would that be possible?
> Are fencing operations dependent on underlying hardware for Pacemaker?
> Thanks,
> *Phil Stedman*
> Db2 High Availability Development and Support
> Email: pmstedma at us.ibm.com
> Inactive hide details for Andrei Borzenkov ---07/30/2020 11:02:58
> PM---30.07.2020 22:17, Philippe M Stedman пишет: >Andrei Borzenkov
> ---07/30/2020 11:02:58 PM---30.07.2020 22:17, Philippe M Stedman пишет: >
> From: Andrei Borzenkov <arvidjaar at gmail.com>
> To: developers at clusterlabs.org, Philippe M Stedman
> <pmstedma at us.ibm.com>, nwahl at redhat.com
> Cc: Toby Haynes <thaynes at ca.ibm.com>, Gerry R Sommerville
> <gerry at ca.ibm.com>, Alan Y Lee <ykalee at ca.ibm.com>
> Date: 07/30/2020 11:02 PM
> Subject: [EXTERNAL] Re: [ClusterLabs Developers] How to implement
> fencing agent with no associated hardware device with Pacemaker?
> ------------------------------------------------------------------------
> 30.07.2020 22:17, Philippe M Stedman пишет:
>> Thanks Gerry.
>> Hi Reid,
>> The shared storage solution we are using has clustering capabilities
> of its
>> own built into it and is able to remotely fence off the lost node, all we
>> need to do is run the command to expel/fence the lost node as part of our
>> own custom fencing agent on the surviving node.
>> FYI, the shared storage solution I am referring to here is IBM Spectrum
>> Scale.
> ...
>>   On Wed, Jul 29, 2020 at 8:34 PM Philippe M Stedman <pmstedma at us.ibm.com>
>>   wrote:
>>     Hi ClusterLabs developers,
>>     I am looking into how to develop a fencing agent for Pacemaker that is
>>     not associated to any underlying hardware device. In our case we have
>>     two servers (we will expand to more in the future) which have
> access to
>>     shared storage. When one of the two nodes fails, we expect the
>>     surviving node to invoke our user-defined fencing agent and run a
>>     series of commands which will "expel" the lost host from accessing
>>     shared storage.
>>     Do you have any advice on how to go about implementing such a
> solution?
>>     All the examples I can find online revolve around using some sort of
>>     underlying hardware device to implement fencing.
> In this case your fencing *is* associated with specific underlying
> hardware device. Just start with any of existing fencing or stonith
> agents and fill in commands to your underlying hardware to fence off
> node. You probably will need some sort of mapping from node name to
> whatever is required by your hardware to identify it.
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