[Pacemaker] Multi-node resource dependency

["Tomcsányi, Domonkos"]

Hello everyone,

I have been struggling with this issue for quite some time so I decided 
to ask you to see if maybe you can shed some light on this problem.
So here is the deal:
I have a 4-node cluster, from which 2-2 nodes belong together.
In ASCII art it would look like this:

--------------         --------------
| NODE1 |    --   | NODE 2  |
--------------         --------------
|                         |
|                         |
|                         |
--------------         --------------
| NODE 3 |  --  | NODE 4 |
--------------         --------------

Now the behaviour I would like to achieve:
If NODE 1 goes offline its services should get migrated to NODE 2 AND 
NODE 3's services should get migrated to NODE 4.
If NODE 3 goes offline its services should get migrated to NODE4 AND 
NODE1's services should get migrated to NODE 2.
Of course the same should happen vice versa with NODE 2 and NODE 4.

The services NODE1 and 2 are the same naturally, but they differ from 
NODE 3's and 4's services. So I added some 'location' directives to the 
config so the services can only be started on the right nodes.
I tried 'colocation' which is great, but not for this kind of behaviour: 
if I colocate both resource groups of NODE 1 and 3 only one of them 
starts (of course, because colocation means the resource/resource 
group(s) should be running on the same NODE, so my location directives 
kick in and prevent for example NODE 3's services from starting on NODE 1).

So my question is: is it possible to define such behaviour I described 
above in Pacemaker? If yes, how?


Thank you so much,
Domonkos