[ClusterLabs] resource cloned group colocations

[Andrei Borzenkov]

On Thu, Mar 2, 2023 at 4:16 PM Gerald Vogt <vogt at spamcop.net> wrote:
>
> On 02.03.23 13:51, Klaus Wenninger wrote:
> >     Now if I stop pacemaker on one of those nodes, e.g. on node ha2, it's
> >     fine. ip2 will be moved immediately to ha3. Good.
> >
> >     However, if pacemaker on ha2 starts up again, it will immediately
> >     remove
> >     ip2 from ha3 and keep it offline, while the services in the group are
> >     starting on ha2. As the services unfortunately take some time to come
> >     up, ip2 is offline for more than a minute.
> >
> >     It seems the colocations with the clone are already good once the clone
> >     group begins to start services and thus allows the ip to be removed
> >     from
> >     the current node.
> >
> >
> > To achieve this you have to add orders on top of collocations.
>
> I don't understand that.
>
> "order" and "colocation" are constraints. They work on resources.
>
> I don't see how I could add an order on top of a colocation constraint...
>

You cannot, but asymmetrical serializing constraint may do it

first start clone then stop ip

when new node comes up, pacemaker builds a transaction which starts
clone on the new node and moves ip (stops on the old node and starts
on the new node). These actions are (should be) part of the same
transaction so serializing constraints should apply.