On Mon, 2011-04-04 at 11:05 +0200, Andrew Beekhof wrote: > On Sat, Mar 19, 2011 at 11:55 AM, Holger Teutsch <holger.teut...@web.de> > wrote: > > Hi Dejan, > > > > On Fri, 2011-03-18 at 14:24 +0100, Dejan Muhamedagic wrote: > >> Hi, > >> > >> On Fri, Mar 18, 2011 at 12:21:40PM +0100, Holger Teutsch wrote: > >> > Hi, > >> > I would like to submit 2 patches of an initial implementation for > >> > discussion. > > .. > >> > To recall: > >> > > >> > crm_resource --move resource > >> > creates a "standby" rule that moves the resource off the currently > >> > active node > >> > > >> > while > >> > > >> > crm_resource --move resource --node newnode > >> > creates a "prefer" rule that moves the resource to the new node. > >> > > >> > When dealing with clones and masters the behavior was random as the code > >> > only considers the node where the first instance of the clone was > >> > started. > >> > > >> > The new code behaves consistently for the master role of an m/s > >> > resource. The options "--master" and "rsc:master" are somewhat redundant > >> > as a "slave" move is not supported. Currently it's more an > >> > acknowledgement of the user. > >> > > >> > On the other hand it is desirable (and was requested several times on > >> > the ML) to stop a single resource instance of a clone or master on a > >> > specific node. > >> > > >> > Should that be implemented by something like > >> > > >> > "crm_resource --move-off --resource myresource --node devel2" ? > >> > > >> > or should > >> > > >> > crm_resource refuse to work on clones > >> > > >> > and/or should moving the master role be the default for m/s resources > >> > and the "--master" option discarded ? > >> > >> I think that we also need to consider the case when clone-max is > >> less than the number of nodes. If I understood correctly what you > >> were saying. So, all of move slave and move master and move clone > >> should be possible. > >> > > > > I think the following use cases cover what can be done with such kind of > > interface: > > > > crm_resource --moveoff --resource myresource --node mynode > > -> all resource variants: check whether active on mynode, then create > > standby constraint > > > > crm_resource --move --resource myresource > > -> primitive/group: convert to --moveoff --node `current_node` > > -> clone/master: refused > > > > crm_resource --move --resource myresource --node mynode > > -> primitive/group: create prefer constraint > > -> clone/master: refused > > Not sure this needs to be refused.
I see the problem that the node where the resource instance should be moved off had to be specified as well to get predictable behavior. Consider a a 2 way clone on a 3 node cluster. If the clone is active on A and B what should crm_resource --move --resource myClone --node C do ? This would require an additional --from-node or similar. > Other than that the proposal looks sane. > > My first thought was to make --move behave like --move-off if the > resource is a clone or /ms, but since the semantics are the exact > opposite, that might introduce introduce more problems than it solves. That was my perception as well. > > Does the original crm_resource patch implement this? No, I will submit an updated version later this week. - holger _______________________________________________ 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
