[Pacemaker] Pacemaker remote nodes, naming, and attributes

[Lindsay Todd]

I built a set of rpms for pacemaker 1.1.0-rc4 and updated my test cluster
(hopefully won't be a "test" cluster forever), as well as my VMs running
pacemaker-remote.  The OS everywhere is Scientific Linux 6.4.  I am wanting
to set some attributes on remote nodes, which I can use to control where
services run.

The first deviation I note from the documentation is the naming of the
remote nodes.  I see:

Last updated: Wed Jun 19 16:50:39 2013
Last change: Wed Jun 19 16:19:53 2013 via cibadmin on cvmh04
Stack: cman
Current DC: cvmh02 - partition with quorum
Version: 1.1.10rc4-1.el6.ccni-d19719c
8 Nodes configured, unknown expected votes
49 Resources configured.


Online: [ cvmh01 cvmh02 cvmh03 cvmh04 db02:vm-db02 ldap01:vm-ldap01
ldap02:vm-ldap02 swbuildsl6:vm-swbuildsl6 ]

Full list of resources:


and so forth.  The "remote-node" names are simply the hostname, so the
vm-db02 VirtualDomain resource has a remote-node name of db02.  The
"Pacemaker Remote" manual suggests this should be displayed as "db02", not
"db02:vm-db02", although I can see how the latter format would be useful.

So now let's set an attribute on this remote node.  What name do I use?
 How about:

# crm_attribute --node "db02:vm-db02" \
     --name "service_postgresql" \
     --update "true"
Could not map name=db02:vm-db02 to a UUID
Please choose from one of the matches above and suppy the 'id' with
--attr-id


Perhaps not the most informative output, but obviously it fails.  Let's try
the unqualified name:

# crm_attribute --node "db02" \
     --name "service_postgresql" \
     --update "true"
Remote-nodes do not maintain permanent attributes,
'service_postgresql=true' will be removed after db02 reboots.
Error setting service_postgresql=true (section=status, set=status-db02): No
such device or address
Error performing operation: No such device or address


So a little more informative, but still it fails.  It probably isn't a
surprise that using "crm node" doesn't work too well either (with the
unqualified name, it creates a "db02" node marked as unclean).

Well, that bit about attributes on remote nodes isn't too surprising,
although I wasn't sure until I tried it.  Once I have an invocation that
works, I'm thinking maybe a resource agent could help by looking for a
local file of node attributes and making the appropriate settings.  Or
maybe there is another way to do this?  Meanwhile I need a command to set
attributes that works!

Since I haven't gotten far enough yet to see for myself, I've also wondered
a few things:

   - How do remote nodes impact the size of the largest cluster that can be
   managed?  I can see having many VMs with services on them.  (I also have
   VMs that are not remote nodes.)
   - Do remote nodes affect quorum calculations at all?

Thanks for the help.

/Lindsay
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