[Pacemaker] how to use dlm and clvm with pacemaker ?

denis bonnenfant denis.bonnenfant at diderot.org
Sat Sep 15 16:34:58 EDT 2012

Le 15/09/2012 18:23, denis bonnenfant a écrit :
> Hello,
> I'm currently running in production a 3-nodes 
> corosync/pacemaker/drbd/clvm xen virtualisation cluster, based on 
> debian wheezy.
> Two nodes are running drbd inactive/active setup,
Sorry for the typo it's active/active !

> with clustered VGs (/dev/xen-data) on top of drbd disk for local domUs 
> , and ISCSI target  LV ( /dev/xen-data/iscsi-target)  for the third 
> node with a virtual ip for failover.
> On both nodes another clustered VG is running on the iscsi initiator 
> (/dev/xen-iscsi).
> LV-based DomUs can live migrate between the 2 drbd nodes if they are 
> on drbd VG,  or between all the nodes if they are on the iscsi VG.
> This setup works quite well, except for one point :  sometimes, when a 
> node falls down, dlm is locking down all the lvm layer, causing all 
> nodes to fence each other. The problem is not related with the stacked 
> lvm setup, as it occurs even when no iscsi resources are started.
> This problem is well known, and new versions of cman totally remove 
> dlm_controld.pcmk. But then documentations are quite confusing :
> - 
> http://www.clusterlabs.org/doc/en-US/Pacemaker/1.1/html/Clusters_from_Scratch/apcs02.html 
> advises to run cman from init scripts with a configured 
> /etc/cluster.conf, and then start pacemaker  from init,
> - 
> http://www.clusterlabs.org/doc/en-US/Pacemaker/1.1/html/Clusters_from_Scratch/apcs02s02.html 
> advises to run corosync with a cman plugin, but don't say how to start 
> pacemaker?
> - some other advise to modify controld RA to use directly new 
> dlm_controld (how ? symlink dlm_controld.pcmk ?)
> Before bringing my cluster down, I want to be sure about the best path 
> for upgrading.
> As I'm running redundant rings in corosync, adding cman stuff in my 
> corosync.conf  seems for me the simplest, but in this case, do I still 
> need to configure controld and clvm in crm, or are they completely 
> managed by the cman plugin ? do I need to start pacemaker from 
> corosync config too ?
> http://theclusterguy.clusterlabs.org/post/907043024/introducing-the-pacemaker-master-control-process-for 
> seems to suggest that in my case, with dlm and clvm involved, option 3 
> with cluster.conf is the best approach. But how pacemaker is started 
> in this case,  from init  after cman ?
> Do I need up-to date version of cman, or is debian wheezy  version 
> (3.0.12) ok ?
> Do I need up-to date version of pacemaker, or is debian wheezy version 
> (1.1.7) ?, recompiled with --with-cman ?
> Regards,
> Denis
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