[ClusterLabs] Why do clusters have a name?

[Kristoffer Grönlund]

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.

Cheers,
Kristoffer

> > and sharing the same configuration across all of
> > them,
> 
> Same configuration like, the same file or the same content accross
> different
> files?
> 
> Sorry for being bold...I just don't get it :/
> 
>