[Pacemaker] CMAN integration questions

Vladislav Bogdanov bubble at hoster-ok.com
Thu Mar 24 04:27:22 EDT 2011

23.03.2011 21:38, Pavel Levshin wrote:
> 23.03.2011 15:56, Vladislav Bogdanov:
>> After 1 minute vd01-d takes over DC role.
>> ============
>> Mar 23 10:10:03 vd01-d crmd: [1875]: info: update_dc: Set DC to vd01-d
>> (3.0.5)
> Excuse me, I have not much knowledge of cman integration, but don't you
> think that DC election should be much faster? 

I do. But this could depend on many factors, number of nodes in a
cluster (16 in my case), totem transport used on underlying layer
(UDPU), etc. Probably Andrew can clarify this, I cannot.

> Pacemaker hardly can work without DC. And STONITH of unexpectedly down 
> node should be much faster, too. It's not clear from your log excerpts
> why fencing the node take so long.

I understand. The main point was that fenced does the same much faster
if it has fence devices configured.

I checked this, and fencing by fenced takes only 20 seconds on my setup.
Then DLM unlocks and cluster continues to work. The only drawback is
that node is killed twice, once by fenced, and once by pacemaker. But
this is very minor issue comparing to 3-4 minutes DLM lock.

Maybe it could be possible to make pacemaker fencing faster in this
particular case, but this may require some efforts if it is even possible.


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