[Linux-cluster] qdiskd: change the number of votes while thecluster is up, possible?

[Lon Hohberger]

On Tue, 2006-12-05 at 07:50 +0100, Pena, Francisco Javier wrote:
> > On Tue, 2006-11-28 at 16:20 +0100, Pena, Francisco Javier wrote:
> > > Hello,
> > > 
> > > I am doing some tests with a GFS cluster in our lab. As part of the 
> > > tests, I am trying to upgrade a two-node GFS cluster to 
> > three nodes. 
> > > This usually requires shutting down the cluster, but if we 
> > use qdisk I 
> > > supposed this was not true anymore...
> > 
> > Unfortunately, that's not true -- because cman flipping from 
> > 2->non-2 node mode requires a restart of cman, which qdisk 
> > can't control nor fix. :(
> > 
> > -- Lon
> > 
> 
> Ok, my fault then. I assumed that removing the "two_node=1
> expected_votes=1" options from the cman configuration (as suggested by
> Josef Whiter in a previous thread) was enough to prevent cman from being
> restarted in this scenario.

It should be, but CMAN doesn't know how to change between the modes,
unfortunately.

> So, if I had a three node cluster and wanted to upgrade it to four
> nodes, would the qdiskd number of votes be properly propagated to all
> nodes?

To go from 3..4..N with nothing special.

* Add the new node to the configuration on the running cluster (all 3
should be running).
* ccs_tool update /etc/cluster/cluster.conf
* cman_tool version -r (new_version)
* To be paranoid, I'd use 'scp' to copy cluster.conf to the new node
* Start new node

The *only* time CMAN gets weird is going 2 to anything more than 2.

If you were using qdisk in a 2-node cluster and *did not* have the
two_node="1" set, you could probably go to 3+ nodes without a problem,
but I haven't tried it.

-- Lon
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