[Linux-HA] Election for resources

[Franck Ganachaud]

Thanks for your answers, Dejan and Andrew.

I was thinking about the CIB and you confirmed, good.
It's also very pleasant to understand a little bit more how the cluster 
react especially if you don't put any boundaries.

Thanks again.
Franck.

Andrew Beekhof a écrit :
> On Mon, Apr 21, 2008 at 11:37 AM, Franck Ganachaud
> <franck.ganachaud at ago.fr> wrote:
>   
>> Thanks for your answer, Dejan.
>>
>>  That's the "almost" part I can't figure out.
>>
>>  It seems that from the little knowledge I have of coding science and the
>> source of heartbeat (ahem! yes I did it, I looked at the source), tell me if
>> I'm wrong, pengine picks up the first (index 0) in the allowed nodes list
>> but how is populated this list ?
>>     
>
> It depends on the order in which the nodes appear in the CIB's <nodes/> section.
> In turn, that order is usually determined by the order the nodes
> appeared in ha.cf (or the order they started in if autojoin was
> specified).
>
> But Dejan is right... if you really do prefer one node over another,
> the only reliable way to do this is to make sure they have different
> scores.
>
>   
>>  *Extract from crm\pengine\native.c :
>>  [...]
>>  *    crm_debug_3("Choosing node for %s from %d candidates",
>>            rsc->id, g_list_length(rsc->allowed_nodes));
>>
>>    if(rsc->allowed_nodes) {
>>        rsc->allowed_nodes = g_list_sort(
>>            rsc->allowed_nodes, sort_node_weight);
>>      *  nodes = rsc->allowed_nodes;
>>        chosen = g_list_nth_data(nodes, 0);*
>>    }
>>      return native_assign_node(rsc, nodes, chosen);
>>  *[...]*
>>
>>  Dejan Muhamedagic a écrit :
>>
>>
>>
>>     
>>> Hi,
>>>
>>> On Mon, Apr 21, 2008 at 09:31:49AM +0200, Franck Ganachaud wrote:
>>>
>>>
>>>       
>>>> Hello,
>>>>
>>>> I have a two nodes cluster (nodeA and nodeB) with a set of resources
>>>>         
>> linked together in a group. Nothing tricky.
>>     
>>>> How hearbeat select which node will run the resources? I see lines like
>>>>         
>> this :
>>     
>>>> "pengine: [12684]: info: native_assign_node: 2 nodes with equal score
>>>>         
>> (1) for running the listed resources (chose nodeB):"
>>     
>>>> But I can't figure out a pattern... can anyone enlighten me?
>>>>
>>>>
>>>>         
>>> Since you didn't express a preference where to run the resources
>>> using a location constraint, the cluster (pengine) picks one at
>>> random (or almost random).
>>>
>>> Thanks,
>>>
>>> Dejan
>>>
>>>
>>>
>>>       
>>>> Franck
>>>> _______________________________________________
>>>>
>>>>
>>>>
>>>>         
>