On Wed, 2024-01-31 at 16:37 +0100, lejeczek via Users wrote: > > On 31/01/2024 16:06, Jehan-Guillaume de Rorthais wrote: > > On Wed, 31 Jan 2024 16:02:12 +0100 > > lejeczek via Users <users@clusterlabs.org> wrote: > > > > > On 29/01/2024 17:22, Ken Gaillot wrote: > > > > On Fri, 2024-01-26 at 13:55 +0100, lejeczek via Users wrote: > > > > > Hi guys. > > > > > > > > > > Is it possible to trigger some... action - I'm thinking > > > > > specifically > > > > > at shutdown/start. > > > > > If not within the cluster then - if you do that - perhaps > > > > > outside. > > > > > I would like to create/remove constraints, when cluster > > > > > starts & > > > > > stops, respectively. > > > > > > > > > > many thanks, L. > > > > > > > > > You could use node status alerts for that, but it's risky for > > > > alert > > > > agents to change the configuration (since that may result in > > > > more > > > > alerts and potentially some sort of infinite loop). > > > > > > > > Pacemaker has no concept of a full cluster start/stop, only > > > > node > > > > start/stop. You could approximate that by checking whether the > > > > node > > > > receiving the alert is the only active node. > > > > > > > > Another possibility would be to write a resource agent that > > > > does what > > > > you want and order everything else after it. However it's even > > > > more > > > > risky for a resource agent to modify the configuration. > > > > > > > > Finally you could write a systemd unit to do what you want and > > > > order it > > > > after pacemaker. > > > > > > > > What's wrong with leaving the constraints permanently > > > > configured? > > > yes, that would be for a node start/stop > > > I struggle with using constraints to move pgsql (PAF) master > > > onto a given node - seems that co/locating paf's master > > > results in troubles (replication brakes) at/after node > > > shutdown/reboot (not always, but way too often) > > What? What's wrong with colocating PAF's masters exactly? How does > > it brake any > > replication? What's these constraints you are dealing with? > > > > Could you share your configuration? > Constraints beyond/above of what is required by PAF agent > itself, say... > you have multiple pgSQL cluster with PAF - thus multiple > (separate, for each pgSQL cluster) masters and you want to > spread/balance those across HA cluster > (or in other words - avoid having more that 1 pgsql master > per HA node) > These below, I've tried, those move the master onto chosen > node but.. then the issues I mentioned. > > -> $ pcs constraint location PGSQL-PAF-5438-clone prefers > ubusrv1=1002 > or > -> $ pcs constraint colocation set PGSQL-PAF-5435-clone > PGSQL-PAF-5434-clone PGSQL-PAF-5433-clone role=Master > require-all=false setoptions score=-1000 >
Anti-colocation sets tend to be tricky currently -- if the first resource can't be assigned to a node, none of them can. We have an idea for a better implementation: https://projects.clusterlabs.org/T383 In the meantime, a possible workaround is to use placement- strategy=balanced and define utilization for the clones only. The promoted roles will each get a slight additional utilization, and the cluster should spread them out across nodes whenever possible. I don't know if that will avoid the replication issues but it may be worth a try. -- Ken Gaillot <kgail...@redhat.com> _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
