I'm setting up a very basic two-node active/passive cluster using Pacemaker 1.1.7 and Corosync 1.4.1 under Red Hat Enterprise Linux 6.3. The cluster is running a web application that needs to be accessed by our separate LAN of desktops.
With only two nodes comprising the cluster I believe a quorum is impossible, so I've set no-quorum-policy to 'ignore'. However I was wondering if there is a possibility of using one or more 'tie breaker' devices/resources to determine a proper quorum? I _think_ I've seen mention of such a thing in passing in this list; I'm not sure. I was thinking I could designate a 'tie breaker' device in the desktop LAN; any node that could access that device - ping it, say - would gain an extra quorum vote, something like that. But then I realized that this could be achieved by simply setting up that LAN device as a proper member of the cluster, with location constraints set to ensure that no resource could ever run on it. Then the normal cluster membership mechanics and quorum calculations would take the third node into account in determining its quorums. If one of the two 'real' nodes couldn't connect to the desktop LAN node then it wouldn't be part of the quorum. What is the proper way to set up a 'tie breaker' situation for a simple two-node Pacemaker cluster? Is there a 'tie breaker' facility - ping a device and get a vote? - or does one just set up a bare-bones third node purely for membership/quorum purposes? I have another question I'd like to ask to properly try and understand how cluster membership works. If I have three nodes, A, B & C, all using unicast UDP, with A & B able to connect to C but not to each other - i.e. A-C works, B-C works, but not A-B - will the three nodes all be seen as connected in a single quorum/group? If not, what happens? In wondering about this I realized that I didn't know if Corosync requires _direct_ communication between all cluster nodes or if nodes can 'relay' transmissions between machines that can't contact each other directly. Will C 'relay' connectivity/membership between A & B? Thank you for any help! _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
