On Thu, Jul 21, 2011 at 4:13 PM, pskrap <psk...@hotmail.com> wrote: > Devin Reade <gdr@...> writes: > >> >> --On Wednesday, July 20, 2011 09:19:33 AM +0000 pskrap <pskrap@...> >> wrote: >> >> > I have a cluster where some of the resources cannot run on the same node. >> > All resources must be running to provide a functioning service. This >> > means that a certain amount of nodes needs to be up before it makes >> > sense for the cluster to start any resources. >> >> Without knowing anything about your application, I would tend to question >> this statement. Is it true that you must not start *any* resources before >> you have enough nodes, or is sufficient to say that the application >> is not considered up until all resources are started? It may not >> make sense to run any, but does it do any harm? >> >> If you *can* start at least some resources before all nodes are available, >> then I would expect that you could get by with defining colocation >> constraints to ensure that some resources don't run on the same nodes, >> perhaps augmenting things with some order constraints if necessary. >> >> If your applications die or do other horrible stuff when only some subset >> are running then I'd have a talk with your application developers >> as it sounds like a larger robustness problem. >> >> Devin >> > > No, there are no crash issues etc when all resources are not running. The > application is just not usable until all resources are started. > > As for the harm, the resources which have constraints preventing them from > running will fail,
Are you talking about constraints in the pacemaker config or some other kind? > but I guess they will recover as more nodes are added. The > harm is mostly in the fact that starting nodes one by one will cause the > resources to be unevenly distributed over the nodes since everything will > start > on the nodes in the order they are installed. I know I can give a preferred > node to a resource and allow it to relocate when it becomes available. > However, > this application provides a real-time service so I only want resources to > relocate when it is absolutely necessary. Therefore I have given the resources > a preferred node, but do not allow them to relocate when it becomes available. > > So I guess the overall harm is limited even though it exists. I was just > looking for a cleaner startup for the system. Since you did not mention any > way > to do what my question was about I assume it is currently not possible to do > what I asked for. I do think such an option would be useful though. Logically > it does not make sense for the cluster to be starting resources for an > application before the cluster have enough nodes for the application to be > able > to run. > > > > _______________________________________________ > Pacemaker mailing list: Pacemaker@oss.clusterlabs.org > http://oss.clusterlabs.org/mailman/listinfo/pacemaker > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: > http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker > _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
