[Pacemaker] Design: 8 vs 4x2 nodes Cluster

[martin.braun at icw.de]

Hi there,
I want to realize a rather complex setup, so I have a couple of questions: 


The cluster (as a shared nothing variant) should provide:

* 4 services (=server) depending on each other. 
* 3 of them can only be realized as active/passive failover, synched with 
DRBD (M/S) 
* The servers running the application will be Virtual Machines. So I will 
end up with three master-slave pairs each providing a VIP with a shared 
drbd-device in a master-slave setup. 
Most resources could only run on one of two distinct server nodes 
(active/passive). In sum I will have eight nodes resp. VMs
Would you recommend the administration of all nodes with a common 
corosync/pacemaker cluster? 
I am a bit afraid of having too many location and collocation constraints 
for all these resources. Is there a way to define subclusters? How would 
one bind a resource group to specific nodes - as a constraint to 
hostnames? 

Or would it be better to have 4 two node clusters communicating on 
disjunct/ subnets, with the advantage of a less complex crm configuration?

Is there a neat method to administer four separate clusters from a console 
or workstation? 
Without introducing a new SPOF? 


Thanks in advance,

Martin




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