[Linux-cluster] Is heuristic really required?

[Lon Hohberger]

On Wed, 2008-04-23 at 16:11 -0400, Charlie Brady wrote:
> On Fri, 18 Apr 2008, HarriPäiväniemi wrote:
> 
> > Qdisk man says at least 1 heuristic is reguired.
> > 
> > Is it?
> > 
> > I have (accidentally) tested and to my mind it worked fine without
> > heuristics. I gave 1 vote to quorumd and no <heuristic>- tag at all and
> > it seemed to work normally like 3-vote cluster should...

You don't need a heuristic (it will run without one).  However, it
doesn't provide much benefit without one.  It's supposed to use
"master-wins" mode if no heuristic is provided to avoid a fence-race -
but it currently doesn't provide that guarantee.


> Another thing I've noticed (with RHEL4 RHC) is the the quorum disk doesn't 
> show up in the node list of the first node set up in the cluster, and 
> doesn't contribute a vote. Anyone have any ideas about that?

It's not really a node, and is not reported by CMAN in the nodes list as
it is in RHEL5/STABLE2 branches.

You can see the votes (assuming each node gets one vote) by looking @
cman_tool status:

  [root at red cluster]# cman_tool status
  Protocol version: 5.0.1
  Config version: 187
  Cluster name: rhel4test1
  Cluster ID: 44365
  Cluster Member: Yes
  Membership state: Cluster-Member
  Nodes: 2
  Expected_votes: 3
  Total_votes: 3
  Quorum: 2   
  Active subsystems: 4
  ...

Nodes: 2 but Total_votes: 3 => last vote comes from qdiskd

-- Lon