17.03.2011 11:05, Andrew Beekhof:
You don't need fake RAs. The cluster will behave just fine if the RA is missing, just not if it's present and reports bogus status
To be precise, the cluster will behave fine if the RA is missing, and cluster tries to "monitor", and all infrastructure works fine (so return code "not installed" is not lost somewhere as it have been in my case two weeks ago). So this cluster will not tolerate, for example, some network faults. It's a strange feature for a fault-tolerant cluster.
Also this design conflicts with idea of "quorum node", which is not supposed to run resources. Quorum node, by it's existence only, may cause resource failure!
It will not work also in the case when two resources are using one RA, and one of those resources is not applicable to a node. Resource agent will be here, returning something like "not configured". Here come in fake RAs, one per resource.
To be impartial, I would like to know what good do you see in the current design, for the case of asymmetrical cluster or quorum node. What's good in checking a resource status on nodes where the resource can not exist? What justifies increased resource downtime caused by monitor failures, which are inevitable in real world?
Is it a kind of automation? But it saves nothing, because cluster administrator if forced to delete unused RAs after every installation, upgrade and even some reconfigurations.
You are stating that RAs must be reliable. It is a good point. But even the Earth is not completely round, and any program may fail, even if it is bug-free, due to external problems. Are we concerned about fault tolerance and high availability? If so, then we should think of erroneous or disastrous conditions.
-- Pavel Levshin _______________________________________________ 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
