On Tue, Sep 27, 2011 at 5:07 PM, Vladislav Bogdanov <bub...@hoster-ok.com> wrote: > 27.09.2011 08:59, Andrew Beekhof wrote: > [snip] >>>>>>> I agree with Jiaju >>>>>>> (https://lists.linux-foundation.org/pipermail/openais/2011-September/016713.html), >>>>>>> that could be solely pacemaker problem, because it probably should >>>>>>> originate fencing itself is such situation I think. >>>>>>> >>>>>>> So, using pacemaker/dlm with openais stack is currently risky due to >>>>>>> possible hangs of dlm_lockspaces. >>>>>> >>>>>> It shouldn't be, failing to connect to attrd is very unusual. >>>>> >>>>> By the way, one of underlying problems, which actually made me to notice >>>>> all this, is that pacemaker cluster does not fence its DC if it leaves >>>>> the cluster for a very short time. That is what Jiaju told in his notes. >>>>> And I can confirm that. >>>> >>>> Thats highly surprising. Do the logs you sent display this behaviour? >>> >>> They do. Rest of the cluster begins the election, but then accepts >>> returned DC back (I write this from memory, I looked at logs Sep 5-6, so >>> I may mix up something). >> >> Actually, this might be possible - if DC.old came back before DC.new >> had a chance to get elected, run the PE and initiate fencing, then >> there would be no need to fence. >> > > (text below is for pacemaker on top of openais stack, not for cman) > > Except dlm lockspaces are in kern_stop state, so a whole dlm-related > part is frozen :( - clvmd in my case, but I expect the same from gfs2 > and ocfs2. > And fencing requests originated on CPG NODEDOWN event by dlm_controld > (with my patch to dlm_controld and your patch for > crm_terminate_member_common()) on a quorate partition are lost. DC.old > doesn't accept CIB updates from other nodes, so that fencing requests > are discarded.
All the more reason to start using the stonith api directly. I was playing around list night with the dlm_controld.pcmk code: https://github.com/beekhof/dlm/commit/9f890a36f6844c2a0567aea0a0e29cc47b01b787 > > I think that problem is that membership changes are handled in a > non-transactional way (?). Sounds more like the dlm/etc is being dumb - if the host is back and healthy, why would we want to shoot it? > If pacemaker fully finish processing of one membership change - elect > new DC on a quorate partition, and do not try to take over dc role (or > release it) on a non-quorate partition if quorate one exists, that > problem could be gone. Non quorate partitions still have a DC. They're just not supposed to do anything (depending on the value of no-quorum-policy). > I didn't dig into code so much, so all above is just my deduction which > may be completely wrong. > And of course real logic could (should) be much more complicated, with > handling of just rebooted members, etc. > > (end of openais specific part) > >>> [snip] >>>>>>> Although it took 25 seconds instead of 3 to break the cluster (I >>>>>>> understand, this is almost impossible to load host so much, but >>>>>>> anyways), then I got a real nightmare: two nodes of 3-node cluster had >>>>>>> cman stopped (and pacemaker too because of cman connection loss) - they >>>>>>> asked to kick_node_from_cluster() for each other, and that succeeded. >>>>>>> But fencing didn't happen (I still need to look why, but this is cman >>>>>>> specific). >>> >>> Btw this part is tricky for me to understand the underlying logic: >>> * cman just stops cman processes on remote nodes, disregarding the >>> quorum. I hope that could be fixed in corosync If I understand one of >>> latest threads there right. >>> * But cman does not do fencing of that nodes, and they still run >>> resources. And this could be extremely dangerous under some >>> circumstances. And cman does not do fencing even if it has fence devices >>> configure in cluster.conf (I verified that). >>> >>>>>>> Remaining node had pacemaker hanged, it doesn't even >>>>>>> notice cluster infrastructure change, down nodes were listed as a >>>>>>> online, one of them was a DC, all resources are marked as started on all >>>>>>> (down too) nodes. No log entries from pacemaker at all. >>>>>> >>>>>> Well I can't see any logs from anyone to its hard for me to comment. >>>>> >>>>> Logs are sent privately. >>>>> >>>>>> >>> >>> Vladislav >>> >>> >>> _______________________________________________ >>> 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 > > > _______________________________________________ > 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