[Cluster-devel] fence daemon problems

[David Teigland <teigland@redhat.com>]

On Wed, Oct 03, 2012 at 04:26:35PM +0000, Dietmar Maurer wrote:
> > I guess you're talking about the dlm_tool ls output? 
> 
> Yes.
> 
> > The "fencing" there
> > means it is waiting for fenced to finish fencing before it starts dlm recovery.
> > fenced waits for quorum.
> 
> So who actually starts fencing when cluster is not quorate? rgmanager?

fenced always starts fencing, but it waits for quorum first.  In other
words, if your cluster looses quorum, nothing happens, not even fencing.

The intention of that is to prevent an inquorate node/partition from
killing a quorate group of nodes that are running normally.  e.g. if a 5
node cluster is partitioned into 2/3 or 1/4.  You don't want the 2 or 1
node group to fence the 3 or 4 nodes that are fine.

The difficult cases, which I think you're seeing, are partitions where no
group has quorum, e.g. 2/2.  In this case we do nothing, and the user has
to resolve it by resetting some of the nodes.  You might be able to assign
different numbers of votes to reduce the likelihood of everyone loosing
quorum.