7 juillet 2015 16:10 "Ken Gaillot" <[email protected]> a écrit: > On 07/07/2015 04:19 AM, Nicolas S. wrote: > >> Hello everybody, >> >> I'm posting first time on this mailing list for an advice. >> >> I try actually trying to build a cluster on Centos 7. >> >> The cluster has 3 nodes : >> >> - 1 virtual machine (machine1). This machine is supposed to be high-available >> - 2 physical machines identical (machine2 and 3) >> >> The physical machines are supposed to use DRBD to replicate storage. >> A shared volume is going to be mounted on both machine 2 and 3 in read/write >> (gfs2). >> >> The virtual machine is only here for the vote in the qorum, it has no data . >> >> I m' following this guide : >> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html/Clusters_from_Scratch/index.html >> >> My questions are : >> >> - Is this configuration OK or shoud I better go to a 2 node only cluster ? > > Hi Nicolas,
Hi Ken , and all the others, > > As others mentioned, the VM is useful as a quorum node only if it's not > running on one of the other cluster nodes. If the VM is itself a highly > available resource started by the cluster, then it should not be a > cluster node. (It can potentially be a pacemaker_remote node, but that's > an advanced topic that you don't need at this stage.) > It's my case the VM isn't a resource of the cluster it's a distant machine only here for quorum. For the moment this cluster is only a proof of concept. > CentOS 7 has corosync 2, which has good support for 2-node clusters. If > you're following Clusters From Scratch, pcs will configure corosync > appropriately for you. > For the moment the documentation is very useful, I just maybe missed the contraint chapter. >> - Is there a way to "group" the storage machines 2 and 3 and put some >> ressources (like DRBD and >> GFS2) only on them ? So that the machine 1 is here , but does nothing, just >> vote. >> I looked around in the pcs command line option but maybe i missed it. >> Thanks in advance > > Yes, "location constraints" do that. See the pcs man page under > "constraint" or the Pacemaker Explained manual for details, but > basically you can tie particular resources to particular nodes either > positively (prefer this node) or negatively (avoid this node). > > There are also colocation constraints to say that certain resources > should be kept together, and order constraints to say that certain > resources should be started/stopped sequentially. > Thank to all for the advice. I ll try to make the constraints for this : - I made my cluster in 'in-opt' (followed redhat doc) , so symmetric-cluster is false and resource cannot go everywhere - drbd / clvm / gfs start only on the storage node (pcs constraint location res_XXX prefers node1=200 , same for node 2 ) - constraint to launch gfs after clvm, wich starts after drbd I'm not yet familiar with dlm and clvm but it will come ... Thanks to all. > _______________________________________________ > Users mailing list: [email protected] > http://clusterlabs.org/mailman/listinfo/users > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: http://bugs.clusterlabs.org _______________________________________________ Users mailing list: [email protected] http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
