Hi Klaus, On 8 Jun 2011, at 22:21, Klaus Darilion wrote: > Hi! > > Currently I have a 2 node cluster and I want to add a 3rd node to use > quorum to avoid split brain. > > The service (DRBD+DB) should only run either on node1 or node2. Node3 > can not provide the service - it should just help the other nodes to > find out if their network is broken or the other node's network is broken. > > Is my idea useful?
Yes. That is what we do for all our Pacemake based setups. > How do I add such a "simple" 3rd node - just by using location > constraints for the service to be run only on node1 or node2? Here is an example: root@cerberus:~# crm configure show node cerberus \ attributes standby="off" node minotaur \ attributes standby="off" node yoda \ attributes standby="off" primitive res_drbd ocf:linbit:drbd \ params drbd_resource="vmstore" primitive res_filesystem ocf:heartbeat:Filesystem \ params fstype="xfs" device="/dev/drbd0" directory="/vmstore" options="noatime,barrier,largeio,logbufs=8,logbsize=256k,swalloc" \ meta target-role="Started" primitive res_ip ocf:heartbeat:IPaddr2 \ params ip="172.28.208.50" cidr_netmask="24" broadcast="172.28.208.255" primitive res_nfs_server lsb:nfs-kernel-server group group_vmstore res_filesystem res_nfs_server res_ip ms ms_drbd res_drbd \ meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true" globally_unique="false" location loc_drbd_cerberus ms_drbd 0: cerberus location loc_drbd_minotaur ms_drbd 0: minotaur location loc_vmstore_cerberus group_vmstore 0: cerberus location loc_vmstore_minotaur group_vmstore 0: minotaur colocation col_vmstore inf: group_vmstore ms_drbd:Master order order_vmstore inf: ms_drbd:promote group_vmstore:start property $id="cib-bootstrap-options" \ expected-quorum-votes="3" \ stonith-enabled="false" \ symmetric-cluster="false" \ pe-warn-series-max="100" \ default-action-timeout="10" \ pe-input-series-max="100" \ dc-version="1.0.8-042548a451fce8400660f6031f4da6f0223dd5dd" \ pe-error-series-max="100" \ cluster-infrastructure="openais" \ last-lrm-refresh="1290511853" \ default-resource-stickiness="1000" rsc_defaults $id="rsc-options" \ target-role="started" Let me know if you need anything explained... Best regards, Anton -- Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @) Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK Linux NTFS maintainer, http://www.linux-ntfs.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://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker