Hi,
On Mon, Apr 21, 2008 at 11:37:37AM +0200, Franck Ganachaud 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 ?
Do you mean which nodes are elligible to run resources or the
order of the nodes? For the former, certain historical data plays
part, such as if a particular resource failed to start on that
node and similar. As for the order of nodes, the most important
factor is the score. For example, you can influence the score
using location constraints. If the scores are the same for a set
of nodes, then some heuristics are used, but those are not
documented and may change in future. BTW, why is that important
to you? If you want to run a group on certain node, why not just
set the location constraint. If you don't care where it runs...
what difference does it make then how the cluster decides on
resource locations.
Thanks,
Dejan
> *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);
The clue is in sort_node_weight.
> * nodes = rsc->allowed_nodes;
> chosen = g_list_nth_data(nodes, 0);*
> }
> return native_assign_node(rsc, nodes, chosen);
> *[...]*
>
> Dejan Muhamedagic a ?crit :
>> 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
>>> _______________________________________________
>>>
>>>
>
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