[ClusterLabs] Why do clusters have a name?

[Jehan-Guillaume de Rorthais]

On Wed, 27 Mar 2019 12:31:00 +0100
Kristoffer Grönlund <kristoffer.gronlund at suse.com> wrote:

> On Wed, 2019-03-27 at 12:25 +0100, Jehan-Guillaume de Rorthais wrote:
> > On Wed, 27 Mar 2019 10:20:21 +0100
> > Kristoffer Grönlund <kristoffer.gronlund at suse.com> wrote:
> >   
> > > On Wed, 2019-03-27 at 10:13 +0100, Jehan-Guillaume de Rorthais
> > > wrote:  
> > > > On Wed, 27 Mar 2019 09:59:16 +0100
> > > > Kristoffer Grönlund <kristoffer.gronlund at suse.com> wrote:
> > > >     
> > > > > On Wed, 2019-03-27 at 08:27 +0100, Ivan Devát  wrote:    
> > > > > > On 26. 03. 19 21:12, Brian Reichert wrote:      
> > > > > > > This will sound like a dumb question:
> > > > > > > 
> > > > > > > The manpage for pcs(8) implies that to set up a cluster,
> > > > > > > one
> > > > > > > needs
> > > > > > > to provide a name.
> > > > > > > 
> > > > > > > Why do clusters have names?
> > > > > > > 
> > > > > > > Is there a use case wherein there would be multiple
> > > > > > > clusters
> > > > > > > visible
> > > > > > > in an administrative UI, such that they'd need to be
> > > > > > > differentiated?
> > > > > > >       
> > > > > > 
> > > > > > For example in a web UI of pcs is a page with multiple
> > > > > > clusters.
> > > > > >       
> > > > > 
> > > > > We use cluster names and rules to apply the same exact CIB to
> > > > > multiple
> > > > > clusters, particularly when configuring geo clusters.    
> > > > 
> > > > I'm not sure to understand. Is it possible to have multiple
> > > > Pacemaker
> > > > daemon instances on the same serveurs?
> > > > 
> > > > Or do you mean it is possible to have multiple namespace where
> > > > resources are
> > > > isolated in and one Pacemaker daemon to manage them?
> > > >     
> > > 
> > > I am not sure what you mean by the second, but I am fairly sure I
> > > don't
> > > mean either of those :) I'm talking about having multiple actual,
> > > distinct clusters  
> > 
> > distinct cluster of Pacemaker/corosync daemons on the same servers or
> > distinct
> > cluster of servers?
> >   
> 
> Distinct clusters of servers:
> 
> Cluster "Tokyo" consisting of node A, B, C
> Cluster "Stockholm" consisting of node D, E, F
> Cluster "New York" consisting of node G, H, I
> 
> All with the same CIB XML document.
> 
> Using tickets, resources can then be moved from one cluster to the
> other, or cloned across multiple clusters. A cluster of clusters, if
> you will.

OK, thanks!