[ClusterLabs] Booth ticket multi-site and quorum /Pacemaker

[Viet Nguyen]

Hi,

Thank you so so much for your help. May i ask a following up question:

For the option of having one big cluster with 4 nodes without booth, then,
if one site (having 2 nodes) is down, then the other site does not work as
it does not have quorum, am I right? Even if we have a quorum voter in
either site A or B, then, if the site with quorum down, then, the other
site does not work.  So, how can we avoid this situation as I want
that if one site is down, the other site still services?

Regards,
Viet

On Wed, 23 Feb 2022 at 17:08, Jan Friesse <jfriesse at redhat.com> wrote:

> Viet,
>
> On 22/02/2022 22:37, Viet Nguyen wrote:
> > Hi,
> >
> > Could you please help me out with this question?
> >
> > I have 4 nodes cluster running in the same network but in 2 different
> sites
> > (building A - 2 nodes and building B - 2 nodes). My objective is to
> > setup HA for this cluster with pacemaker. The expectation is if a site is
> > down, the other site still services.
> >
> >  From what I could understand so far, in order to make it work, it needs
> to
> > have booth ticket manager installed in a different location, let's say
> > building C which connects to both sites A and B.
> >
> > With this assumption, i would like to ask few questions:
> >
> >     1. Am i right that I need to setup the booth ticket manager as a
> quorum
> >     voter as well?
>
> Yes, booth (arbitrator) has to be installed on "site" C if you want to
> use booth. Just keep in mind booth has nothing to do with quorum.
>
> >     2. What happens if  the connection between site A and B is down, but
> the
> >     connection between A and C, B and C still up? In this case, both
> site A and
> >     B still have the quorum as it can connect to C, but not between each
> other?
>
> If you use booth then it's not required site A to see site B. It's then
> "site" C problem to decide which site gets ticket.
>
>
> >     3. Or is there any better way to manage 2 sites cluster, each has 2
> >     nodes? And if one site is down like environmental disaster, then,
> the other
> >     site still services.
>
> Basically there are (at least) two possible solutions:
> - Have one big cluster without booth and use pcmk constraints
> - Have two 2 node clusters and use booth. Then each of the two node
> clusters is "independent" (have its own quorum) and each of the cluster
> runs booth (site) as a cluster resource + "site" C running booth
> (arbitrator)
>
> Regards,
>    Honza
>
> >
> >
> > Thank you so much for your help!
> > Regards,
> > Viet
> >
> >
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