[ClusterLabs] how to set a dedicated fence delay for a stonith agent ?

[Klaus Wenninger]

On 06/28/2017 05:29 PM, Klaus Wenninger wrote:
> On 05/08/2017 09:20 PM, Lentes, Bernd wrote:
>> Hi,
>>
>> i remember that digimer often campaigns for a fence delay in a 2-node  cluster.
>> E.g. here: http://oss.clusterlabs.org/pipermail/pacemaker/2013-July/019228.html
>> In my eyes it makes sense, so i try to establish that. I have two HP servers, each with an ILO card.
>> I have to use the stonith:external/ipmi agent, the stonith:external/riloe refused to work.
>>
>> But i don't have a delay parameter there.
>> crm ra info stonith:external/ipmi:
>>
>> ...
>> pcmk_delay_max (time, [0s]): Enable random delay for stonith actions and specify the maximum of random delay
>>     This prevents double fencing when using slow devices such as sbd.
>>     Use this to enable random delay for stonith actions and specify the maximum of random delay.
>> ...
>  
> Sorry for resurrecting this but
> https://github.com/ClusterLabs/pacemaker/commit/3e3cf385e0c9780fc95a4491703413b3dad54eb3
> might be of interest.

Or a little bit more readable ;-)

pcmk_delay_max: Enable random delay for stonith actions and specify
                the maximum of random delay
                This prevents double fencing when using slow devices
                such as sbd.
                Use this to enable random delay for stonith actions.
                The overall delay is derived from a random delay value
                adding a static delay so that the sum is kept below
                the maximum delay.

pcmk_delay_base: Enable base delay for stonith actions and specify
                 base delay value
                 This prevents double fencing when different delays
                 are configured on the nodes. Use this to enable
                 static delay for stonith actions.
                 The overall delay is derived from a random delay
                 value adding a static delay so
                 that the sum is kept below the maximum delay.

Regards,
Klaus

>> This is the only delay parameter i can use. But a random delay does not seem to be a reliable solution.
>>
>> The stonith:ipmilan agent also provides just a random delay. Same with the riloe agent.
>>
>> How did anyone solve this problem ?
>>
>> Or do i have to edit the RA (I will get practice in that :-))?
>>
>>
>> Bernd
>>
>>
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-- 
Klaus Wenninger

Senior Software Engineer, EMEA ENG Openstack Infrastructure

Red Hat

kwenning at redhat.com