Building a shared storage cluster without fencing is asking for
heart-ache. There is no case, quorum or not, where it is ok to skip
fencing. If a node locks up mid-write and the other node simply assumes
it's dead, cleans up and goes on using storage without coordinating with
the peer, and then the peer recovers and continues writing, you've just
corrupted your data.
Please use fencing.
On 08/07/13 09:35, Andrew Morgan wrote:
Thanks Florian.
The problem I have is that I'd like to define a HA configuration that
isn't dependent on a specific set of fencing hardware (or any fencing
hardware at all for that matter) and as the stack has the quorum
capability included I'm hoping that this is an option.
I've not been able to find any quorum commands within pcs; the closest
I've found is setting a node to "standby" but when I do that, it appears
to have lost its quorum vote - this seems at odds with the help text....
standby <node>
Put specified node into standby mode (the node specified will
no longer be able to host resources
Regards, Andrew.
On 8 July 2013 10:23, Florian Crouzat <gen...@floriancrouzat.net
<mailto:gen...@floriancrouzat.net>> wrote:
Le 08/07/2013 09:49, Andrew Morgan a écrit :
I'm attempting to implement a 3 node cluster where only 2 nodes are
there to actually run the services and the 3rd is there to form
a quorum
(so that the cluster stays up when one of the 2 'workload' nodes
fails).
To this end, I added a location avoids contraint so that the
services
(including drbd) don't get placed on the 3rd node (drbd3)...
pcs constraint location ms_drbd avoids drbd3.localdomain
the problem is that this constraint doesn't appear to be
enforced and I
see failed actions where Pacemaker has attempted to start the
services
on drbd3. In most cases I can just ignore the error but if I
attempt to
migrate the services using "pcs move" then it causes a fatal startup
loop for drbd. If I migrate by adding an extra location contraint
preferring the other workload node then I can migrate ok.
I'm using Oracle Linux 6.4; drbd83-utils 8.3.11; corosync 1.4.1;
cman
3.0.12.1; Pacemaker 1.1.8 & pcs 1.1.8
I'm no quorum-node expert but I believe your initial design isn't
optimal.
You could probably even run with only two nodes (real nodes) and
no-quorum-policy=ignore + fencing (for data integrity) [1]
This is what most (all?) people with two nodes clusters do.
But if you really believe you need to be quorate, then I think you
need to define your third node as quorum-node in corosync/cman (not
sure how since EL6.4 and CMAN) and I cannot find a valid link. IIRC
with such definition, you won't need the location constraints.
[1]
http://clusterlabs.org/doc/en-__US/Pacemaker/1.1-plugin/html/__Clusters_from_Scratch/___perform_a_failover.html#___quorum_and_two_node_clusters
<http://clusterlabs.org/doc/en-US/Pacemaker/1.1-plugin/html/Clusters_from_Scratch/_perform_a_failover.html#_quorum_and_two_node_clusters>
--
Cheers,
Florian Crouzat
_________________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
<mailto:Pacemaker@oss.clusterlabs.org>
http://oss.clusterlabs.org/__mailman/listinfo/pacemaker
<http://oss.clusterlabs.org/mailman/listinfo/pacemaker>
Project Home: http://www.clusterlabs.org
Getting started:
http://www.clusterlabs.org/__doc/Cluster_from_Scratch.pdf
<http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf>
Bugs: http://bugs.clusterlabs.org
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://bugs.clusterlabs.org
--
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://bugs.clusterlabs.org
