How to configure PAF for two clusters from two different data centers

[RajasekarArumugam28]

Hi,

I have 3 node (Master and 2 slave) setup in primary site and DR site. I have Pacemaker configure on both sites and I want to clarity how to configure replication between two data center masters. Please help.

[Markus-]

So you have a geo cluster using boothd or just two separate Clusters?

[RajasekarArumugam28]

Two separate clusters (below is the output of one of the cluster and we have same setup in another location)

Node List:

• Online: [ pg0 pg1 pg2 ]

Full List of Resources:

• MASTER (ocf::pacemaker:Dummy): Started pg0
• vip (ocf::heartbeat:IPaddr2): Started pg0
• mgmt_vip (ocf::heartbeat:IPaddr2): Started pg0
• Clone Set: pgsql-ha [pgsqld] (promotable):
  • Masters: [ pg0 ]
  • Slaves: [ pg1 pg2 ]

[RajasekarArumugam28]

Hi @Markus- any help is highly appreciated.

[Markus-]

If you have two different clusters, the PAF could not help. The PAF is used in one single PostgreSQL-Cluster.

[RajasekarArumugam28]

Hi @Markus- are you saying it is not possible to configure replication between two clusters with PAF

[Markus-]

This is not possible.

[ioguix]

Hi,

I'm not entirely sure it's not possible. You can probably setup a "promoted" cluster on one side and an "unpromoted" one on the other side using cascading replication.

You might be able to use target-role to keep your promotable resource as unpromoted on one side and set it to promoted on the other side, by hand. See: https://clusterlabs.org/pacemaker/doc/2.1/Pacemaker_Explained/singlehtml/#resource-meta-attributes

You might be able to use booth ticket as well, constraining the promoted role to a ticket.

The challenging part is how you setup the cascading replication so all node on the "unpromoted" side does not replicate from the "promoted" side but from a local standby...It might involve some pacemaker rules, or hand setup...

I never tried such setup, but it would be nice to experiment around this.

[RajasekarArumugam28]

I am trying on this and let you know if any queries.

[asphator]

I don't understand the point of having PAF between 2 masters of 2 different clusters... What do you failover then if not the master role ? Could you describe a use case please ?