[ClusterLabs] Antw: [EXT] Colocation per site ?

[Andrei Borzenkov]

On Fri, Feb 19, 2021 at 2:44 PM Strahil Nikolov <hunter86_bg at yahoo.com> wrote:
>
>
> >Do you have a fixed relation between node >pairs and VIPs? I.e. must
> >A/D always get VIP1, B/E - VIP2 etc?
>
> I have to verify it again, but generally speaking - yes , VIP1 is always on nodeA/D (master), VIP2 on nodeB/E (worker1) , etc.
>
> I guess I can set negative constraints (-inf) -> VIP1 on node B/E + nodeC/F, but the stuff with the 'same DC as master' is the tricky part.
>

I am not sure I understand what DC has to do with it. You have two
scale-out SAP HANA instances, one is primary, another is secondary. If
I understand correctly your requirements, your backup application
needs to contact the primary instance which may failover to another
site. You must be using some resource agent for it, to manage
failover. The only one I am aware of is SAPHanaSR-ScaleOut. It already
sets different node properties for primary and secondary sites. Just
use them. If you use something else, just look at what attributes your
RA sets. Otherwise you will be essentially duplicating your RA
functionality because you will somehow need to find out which site is
currently primary.

There is no guarantee that pacemaker DC wil be on the same site as SAP
HANA primary system.