[Linux-cluster] DLM locks with 1 node on 2 node cluster

[David Teigland]

On Mon, Aug 28, 2006 at 11:41:55AM -0400, Zelikov_Mikhail at emc.com wrote:
> I am using the latest cluster from RHEL4 branch. I have 2 node cluster:
> nodes A and B. Node A grabs a lock in the exclusive mode, node B waits for a
> membership change. I manually reset node A at which point node B gets the
> membership change notification and then tries to acquire the lock in the
> exclusive mode. At this point this operations locks forever. Once the node A
> is up DLM returns with the lock acquired for node B - as expected.
> However, if I shutdown node A instead of killing it then everything works as
> expected - Node B gets the notification and the successfully grabs the lock
> w/o locking up.

> Has anybody else seen this? I was wondering if this is a bug or there is
> something special about 2-node clusters, or do I misunderstand how it
> supposed to work?

You're probably not using cman's two_node setting which means the one node
by itself will be blocked by quorum.  When you do a 'cman_tool leave
remove', that reduces the votes required for quorum, so it's not a problem
for the remaining node.  Try using the two_node mode as described here:
  http://sources.redhat.com/cluster/doc/usage.txt

Dave