On Fri, May 25, 2012 at 10:04 AM, Lars Ellenberg <lars.ellenb...@linbit.com> wrote: > On Sun, May 06, 2012 at 09:45:09PM +1000, Andrew Beekhof wrote: >> On Thu, May 3, 2012 at 5:38 PM, Lars Ellenberg >> <lars.ellenb...@linbit.com> wrote: >> > >> > People sometimes think they have a use case >> > for influencing which node will be the DC. >> >> Agreed :-) >> >> > >> > Sometimes it is latency (certain cli commands work faster >> > when done on the DC), >> >> Config changes can be run against any node, there is no reason to go >> to the one on the DC. >> >> > sometimes they add a "mostly quorum" >> > node which may be not quite up to the task of being DC. >> >> I'm not sure I buy that. Most of the load would comes from the >> resources themselves. >> >> > Prohibiting a node from becoming DC completely would >> > mean it can not even be cleanly shutdown (with 1.0.x, no MCP), >> > or act on its own resources for certain no-quorum policies. >> > >> > So here is a patch I have been asked to present for discussion, >> >> May one ask where it originated? >> >> > against Pacemaker 1.0, that introduces a "dc-prio" configuration >> > parameter, which will add some skew to the election algorithm. >> > >> > >> > Open questions: >> > * does it make sense at all? >> >> Doubtful :-) >> >> > >> > * election algorithm compatibility, stability: >> > will the election be correct if some nodes have this patch, >> > and some don't ? >> >> Unlikely, but you could easily make it so by placing it after the >> version check (and bumping said version in the patch) >> >> > * How can it be improved so that a node with dc-prio=0 will >> > "give up" its DC-role as soon as there is at least one other node >> > with dc-prio > 0? >> >> Short of causing an election every time a node joins... I doubt it. > > Where would be a suitable place in the code/fsa to do so?
Just after the call to exit(0) :) I'd do it at the end of do_started() but only if dc-priority* > 0. That way you only cause an election if someone who is likely to win it starts. And people that don't enable this feature are unaffected. * Not dc-prio, its 2012, there's no need to save the extra 4 chars :-) _______________________________________________ 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://bugs.clusterlabs.org