[Pacemaker] Multiple independent two-node clusters side-by-side?

[Andreas Ntaflos]

Hi, 

first time poster, short time Pacemaker user. I don't think this is a 
very difficult question to answer but I seem to be feeding Google the 
wrong search terms. I am using Pacemaker 1.0.8 and Corosync 1.2.0 on 
Ubuntu 10.04.1 Server.

Short version: How do I configure multiple independent two-node clusters 
where the nodes are all on the same subnet? Only the two nodes that form 
the cluster should see that cluster's resources and not any other. 

Is this possible? Where should I look for more and detailed information?

Long version: I have a setup with two physical machines which both run 
multiple virtual machines (Libvirt/KVM). For cluster and heartbeat 
communication there is a dedicated subnet (direct connection between the 
physical hosts) to which all VMs are connected (10.0.0.0/24). DNS is 
running correctly and all nodes are addressable by their 
hostname/nodename.

Initially I set up a simple PostgreSQL/DRBD active/passive cluster on 
two VMs. I generated authkeys for Corosync and copied them to the VMs 
which form that cluster. I was, by the way, delighted how smooth both 
setup and configuration went. All hail to "Cluster from Scratch". 
Everything worked exactly as I had hoped in this two-node cluster.

Now I need to set up another two-node active/passive cluster for a 
different application. Here, too, I generated new authkeys for Corosync 
and copied them to the VMs in question. 

Once the nodes were online and connected to the cluster subnet, however, 
they were able to see the existing cluster and all its resources. The 
CRM also complained about a bunch of "failed actions" because, 
naturally, these two new nodes don't have DRBD and PostgreSQL installed 
and never will. 

crm_mon now shows a four-node cluster where I'd like to (somehow) see 
two two-node clusters with resources independent from each other. I'd 
also like to re-use primitive names on different clusters 
(cluster_main_ip, cluster_admin_ip, ...) and not have to prefix each 
name somehow. I also imagine that the configuration would quickly get 
huge and very unwieldy once there are more than a few nodes involved. I 
also wonder how the Corosync instances on the existing cluster can talk 
to the instances on the new cluster? They have different authkeys, after 
all.

What are my options here? How should the configuration of Pacemaker 
look? Or is that more related to Corosync? Should I configure a 
different subnet for each two-node cluster? 

Please point me to the (section of the) documentation that can help me 
understand how this is supposed to work.

Thanks in advance!

Andreas
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