[Openais] quorum service question

[Christine Caulfield]

On 29/10/09 13:32, Dietmar Maurer wrote:
> Hi all,
>
> I am just testing the quorum service and have some basic questions. First, I use the following configuration in corosync.conf:
>
> quorum {
>          provider: corosync_votequorum
>          expected_votes: 3
>          votes: 1
> }
>
> But AFAIK this information is local (not copied to other nodes). And the votequorum seems to add new nodes dynamically. So how can I make sure that all nodes in the cluster use the same values? I guess it is important that all nodes start with the same value?
>
> Or is it better to not set expected_votes at start:
>
> quorum {
>          provider: corosync_votequorum
> 	  votes: 1
> }
>
> And set expected_votes later with an application that has static knowledge about all cluster members?

The quorum service really works best if you have a common configuration 
system so that the values are the same on all nodes.

Having said that it should always use the highest expected_votes value, 
so as you add nodes (with, I hope, increasing values for 
expected_votes!) then the quorum requirement will increase. So although 
the actual values for expected_votes per node are not replicated, the 
effect is.


> Maybe someone can suggest some further reading on that topic?
>
> And when node loose quorum it logs "[VOTEQ ] quorum lost, blocking activity". But that does not really block anything? Instead any quorum listener gets notified that the quorum is lost?
>

Actually it does block some API operations when there is no quorum - or 
it should. Obviously the quorum APIs are *not* blocked though :-)


Chrissie