<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
If you are running two nodes, you need to tell pacemaker you don't
care if it can't get quorum, by only having 1 of 2 nodes available.
Neither node which take over in this event know if there is split
brain or not, so you will need to make sure you have sufficient
infrastructure between the two to ensure you don't have a split
brain due to a single issue (e.g. switch, cable, port).<br>
<br>
The simplest solution is to add a third node to the cluster, so you
hopefully end up with at least two nodes available during an issue
to retain quorum. If your network dies, then you're going to still
have 3 nodes that won't run any resources, but at that point you
have different problems.<br>
<br>
I've many two node pacemaker clusters with no-quorum-policy set to
ignore, and it works fine. We have multiple interfaces for the
systems to communicate on, which talk via diverse switch
environments. It is a known and accepted risk that if the entire
network fails we will have split brain, but depending on your
workload (e.g. haproxy in this case), split brain probably doesn't
matter too much.<br>
<br>
<br>
<br>
On 6/7/12 7:35 AM, Christian Parpart wrote:
<blockquote
cite="mid:CA+qvzFMOadt9g9h7kqOJAryGtp1gdbpVyxu1r+kQ=1G5D_YNDg@mail.gmail.com"
type="cite">Hey all,
<div><br>
</div>
<div>regarding 2-node clusters for a single service (e.g. HAproxy,
in my case),</div>
<div>when now one node goes down, by server crash, or cable
unplugged,</div>
<div>how does the other still functioning node actually know, that
this is</div>
<div>not a split brain and can take over?</div>
<div><br>
</div>
<div>I also wonder how keepalived tool is managing that, which is
magically working well so far,</div>
<div>but I'd like to migrate to pacemaker/corosync for the new
services.</div>
<div><br>
</div>
<div>Many thanks,</div>
<div>Christian.</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Pacemaker mailing list: <a class="moz-txt-link-abbreviated" href="mailto:Pacemaker@oss.clusterlabs.org">Pacemaker@oss.clusterlabs.org</a>
<a class="moz-txt-link-freetext" href="http://oss.clusterlabs.org/mailman/listinfo/pacemaker">http://oss.clusterlabs.org/mailman/listinfo/pacemaker</a>
Project Home: <a class="moz-txt-link-freetext" href="http://www.clusterlabs.org">http://www.clusterlabs.org</a>
Getting started: <a class="moz-txt-link-freetext" href="http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf">http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf</a>
Bugs: <a class="moz-txt-link-freetext" href="http://bugs.clusterlabs.org">http://bugs.clusterlabs.org</a>
</pre>
</blockquote>
</body>
</html>