On 21/10/13 10:18, Digimer wrote: > On 21/10/13 04:28, Timm Bordeman wrote: >> Hi, >> >> I'm building a two-node cluster based on XenServer, Pacemaker and DRBD. All >> needed resources are configured and correctly handled by pacemaker, but >> currently I'm struggling with stonith / fencing. >> >> Both physical servers are running XenServer and a couple of virtual machines >> which are being mirrored. For example, on each servers is an Apache-VM >> running which share a data partition over DRBD. I configured fencing over >> XEN, which is restarting any faulty VM reliable, as long as both physical >> servers are working correctly. >> >> Unfortunately fencing doesn't work when a server that hosts a faulty virtual >> machine is powered off or not reachable over the network. In this case >> pacemaker does not promote the DRBD partition on the second / passive >> virtual machine to the primary partition. Other resources, like the apache >> server, won't get started. I know that this is an expected behaviour of >> Pacemaker and DRBD, but I'm not sure what is needed to make the failover >> reliable even in the case of a completely broken physical server. Fencing by >> issuing a reboot of the broken server obviously is not an option since the >> server wouldn't come up due to a hardware defect. >> >> I appreciate any help on this. >> >> Thanks, >> Tim > > What fence agent(s) are you trying to use? Proper fencing works > regardless of what state or condition the target node is in. Can you > share your cluster's configuration? > > Also, Lars is correct. You need to disable quorum on 2-node clusters. > This is fine because fencing prevents split-brain conditions, but it > does introduce some configuration issues. Most notably, you want to make > sure that pacemaker does not start on boot. If the network link between > the nodes fails, you can end up in a "fence loop" where the first node > to be fenced boots, starts pacemaker, fails to connect to it's peer and > fences it. > > Cheers >
Woops, s/Lars/Michael/. :) -- 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: [email protected] 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
