[Linux-cluster] question ccsd for multiple clusters on same subnet

[Ofer Inbar]

CentOS 5.3, cman-2.0.115-34.el5_5.3.

Working in a test environment with VMware, setting up test clusters,
so we're not setting up separate VLANs for each cluster (though we
will do that outside this initial test environment).

I accidentally started cman on a new node for a new cluster before I
copied the cluster.conf file I wanted to use into /etc/cluster, and
to my surprise, it picked up a cluster.conf from an older cluster
that's already up and running.  In /var/log/messages, I see:

ccsd[4475]: Unable to parse /etc/cluster/cluster.conf 
ccsd[4475]: Searching cluster for valid copy. 
ccsd[4475]: Remote copy of cluster.conf (version = 15) found. 
ccsd[4475]: Remote copy of cluster.conf is from quorate node. 

This let me to notice the documention of the -P option in ccsd's
man page.  It seems that each ccsd listens on three default ports,
and uses broadcast for some things, such that ccsd's from separate
clusters might potentially see and talk to each other if they don't
have separate VLANs.  I assume this is the reason my new host picked
up a cluster.conf from an unrelated cluster.

However, the documentation is vague and uninformative.  I don't really
know what ccsd uses each port for.  It doesn't even say what the
defaults are (though I can see from lsof that they're 50006,7,8, and
I could experiment to figure out which port was which).  I also don't
know whether there's any standard practice about how to run with
non-default ports (it does look like /etc/init.d/cman looks for an
environment variable named CCSD_OPTS).

If I properly initialize my clusters by copying the right cluster.conf
into place before I first start cman, I won't encounter the specific
problem I had here.  However, does that make it okay, or will I run
into other problems running multiple clusters with ccsd's using the
same ports on the same subnet?

Where can I find documentation about this, aimed at sysadmins?
  -- Cos