I'm familiar with other clustering software and the more traditional approach is to have a quorum requirement (to stop the first node started from grabbing all the cluster resources) but to implement a nominal (and hopefully configurable) timeout, after which the quorum requirement is lifted, allowing the cluster resources to run on whatever nodes are available at that point.
This seems a reasonable and pragmatic compromise to these mutually exclusive requirements and I don't imagine that would be difficult to code. Darren On Tue, 2010-05-11 at 08:10 +0100, Christine Caulfield wrote: > On 10/05/10 23:22, Alan Jones wrote: > > Putting the expected votes to one in both corosync and pacemaker allows > > the cluster > > to start with one node (not what I want). > > Sorry, but you can't have it both ways. Either the cluster is allowed to > run with 1 node or it isn't. There is no rule that says "I want the > cluster to run with only one node ONLY if there were previously 2 nodes > and one died, but not if they were booted at different times". > > Though we do accept patches ;-) > > Chrissie > > > Unfortunately, it also does > > not allow the > > cluster to continue with 1 node after a failure because pacemaker > > remembers the > > two node cluster and increases its expected votes. > > The idea of quorum does not seem to be closely coupled between corosync and > > pacemaker. Running with expected votes of two, I halted a node and then > > used > > corosync-quorumtool to set the surviving nodes votes to two. Now > > corosync says > > it has quorum and pacemaker says it does not; i.e. the resources are not > > able to run. > > To sum up - as far as pacemaker behavior the two_node option does not > > seem to > > do anything. Further, if I plan to do quorum logic in corosync for the > > bahavior > > I want, I will also need to explore how to get pacemaker to use it. > > Any comments are welcome. > > Alan > > > > On Mon, May 10, 2010 at 12:17 AM, Christine Caulfield > > <[email protected] <mailto:[email protected]>> wrote: > > > > On 08/05/10 01:02, Alan Jones wrote: > > > > I'd like to modify the quorum behavior to require 2 nodes to > > start the > > cluster but allow it to continue with only 1 node after a failure. > > It seemed that the two_node option used with the votequorum provider > > might provide what I'm looking for (corosync.conf section below). > > However, I'm getting the first behavior (requiring 2 nodes to start) > > without the second (continute with only 1 node). > > Should I provide a votequorum device to add another vote after a > > failure? > > Any other ideas? > > Alan > > --- > > quorum { > > provider: corosync_votequorum > > expected_votes: 2 > > votes: 1 > > two_node: 1 > > } > > > > > > > > expected_votes should be set to 1 if you're using the two_node > > option. If you set it to 2, then it will always need both nodes to > > be up ... as you've discovered ;-) > > > > Chrissie > > > > > > _______________________________________________ > Openais mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/openais
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