[ClusterLabs] Antw: Re: Antw: Re: 2-Node Cluster Pointless?

[Ulrich Windl]

>>> Andrei Borzenkov <arvidjaar at gmail.com> schrieb am 22.04.2017 um 09:05 in
Nachricht <ede2cdd3-7020-9f59-90ad-c3b4a0c9eba7 at gmail.com>:
> 18.04.2017 10:47, Ulrich Windl пишет:
> ...
>>>
>>> Now let me come back to quorum vs. stonith;
>>>
>>> Said simply; Quorum is a tool for when everything is working. Fencing is
>>> a tool for when things go wrong.
>> 
>> I'd say: Quorum is the tool to decide who'll be alive and who's going to 
> die,
>> and STONITH is the tool to make nodes die.
> 
> If I had PROD, QA and DEV in a cluster and PROD were separated from
> QA+DEV I'd be very sad if PROD were shut down.
> 
> The notion of simple node majority as kill policy is not appropriate as
> well as simple node based delays. I wish pacemaker supported scoring
> system for resources so that we could base stonith delays on them (the
> most important sub-cluster starts fencing first).

So your preference for a 2|1 node split brain scenario is to make the one node
survive if it runs the more important resources?

> 
> 
>> If everything is working you need
>> neither quorum nor STONITH.
>>
> 
> I wonder how SBD fits into this discussion. It is marketed as stonith
> agent, but it is based on committing suicide so relies on well-behaving
> nodes. Which we by definition cannot trust to behave well, otherwise
> we'd not need stonith in the first place.
> 
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