Ken Gaillot <kgail...@redhat.com> wrote: > On 07/20/2016 07:32 PM, Andrew Beekhof wrote: > > On Thu, Jul 21, 2016 at 2:47 AM, Adam Spiers <aspi...@suse.com> wrote: > >> Ken Gaillot <kgail...@redhat.com> wrote: > >>> Hello all, > >>> > >>> I've been meaning to address the implementation of "reload" in Pacemaker > >>> for a while now, and I think the next release will be a good time, as it > >>> seems to be coming up more frequently. > >> > >> [snipped] > >> > >> I don't want to comment directly on any of the excellent points which > >> have been raised in this thread, but it seems like a good time to make > >> a plea for easier reload / restart of individual instances of cloned > >> services, one node at a time. Currently, if nodes are all managed by > >> a configuration management system (such as Chef in our case), > > > > Puppet creates the same kinds of issues. > > Both seem designed for a magical world full of unrelated servers that > > require no co-ordination to update. > > Particularly when the timing of an update to some central store (cib, > > database, whatever) needs to be carefully ordered. > > > > When you say "restart" though, is that a traditional stop/start cycle > > in Pacemaker that also results in all the dependancies being stopped > > too?
No, just the service reload or restart without causing any cascading effects in Pacemaker. > > I'm guessing you really want the "atomic reload" kind where nothing > > else is affected because we already have the other style covered by > > crm_resource --restart. > > crm_resource --restart isn't sufficient for his use case because it > affects all clone instances cluster-wide, whereas he needs to reload or > restart (depending on the service) the local instance only. Exactly. > > I propose that we introduce a --force-restart option for crm_resource which: > > > > 1. disables any recurring monitor operations > > None of the other --force-* options disable monitors, so for > consistency, I think we should leave this to the user (or add it for > other --force-*). > > > 2. calls a native restart action directly on the resource if it > > exists, otherwise calls the native stop+start actions > > What do you mean by native restart action? Systemd restart? > > > 3. re-enables the recurring monitor operations regardless of whether > > the reload succeeds, fails, or times out, etc > > > > No maintenance mode required, and whatever state the resource ends up > > in is re-detected by the cluster in step 3. > > If you're lucky :-) > > The cluster may still mess with the resource even without monitors, e.g. > a dependency fails or a preferred node comes online. Maintenance > mode/unmanaging would still be safer (though no --force-* option is > completely safe, besides check). I'm happy with whatever you gurus come up with ;-) I'm just hoping that it can be made possible to pinpoint an individual resource on an individual node, rather than having to toggle maintenance flag(s) across a whole set of clones, or a whole node. _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org