----- Original Message ----- > From: "Donald Stahl" <d...@blacksun.org> > To: "The Pacemaker cluster resource manager" <pacemaker@oss.clusterlabs.org> > Sent: Thursday, February 21, 2013 9:40:06 AM > Subject: Re: [Pacemaker] Dependency Trees > > > No. > > > > [quote] > > If you say "colocate A with B" and there is nowhere B is allowed to > > run, then A wont be allowed to run either. > > But once the cluster has figured out where they go, it doesn't stop > > them being started in parallel. > > [/quote] > > > > in this case, A = OraListener1 and B = OraBin1 > > > > You only get the "Start A then start B" part by adding the ordering > > constraint. > > I'm not sure I understand where the "sequential" option comes into > play with a colocation set then. > > Or to put it another way- I'm not sure what practical difference > there > is in these examples: > > http://clusterlabs.org/wiki/FAQ#Collocation_Sets
I think you may have missed a key piece - Sets. Requires more than 2 and assumes at least one will be sequential. Here might explain better - have a look at the "Unversioned Docs" at 'General Concepts' - ordering explained and colocation explained. Well into each of the documents they talk about sequential/non-sequential: http://clusterlabs.org/doc/ > > colocation myset inf: app1 app2 > colocation myset inf: ( app1 app2 ) Basics are something like this: colocation myset inf: ( app1 app2 ) app3 app1 and app2 don't care about each other but they both must colocate with app3. App2's locale/status doesn't effect app1 but app3 effects both whereas colocation myset inf: app1 app2 app3 app2 can only run once app3 is placed and app1 can only run once app3 and app2 are placed. > > The first seems to say that app1 is dependent on app2 being able to > run somewhere. > > Does the second one simply say that they must not be split up, but if > only one can run, that's fine? > > -Don > > _______________________________________________ > 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 > > _______________________________________________ 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
