[Pacemaker] Initial quorum

[pskrap]

Andrew Beekhof <andrew at ...> writes:

> 
> On Thu, Jul 21, 2011 at 4:13 PM, pskrap <pskrap at ...> wrote:
> > Devin Reade <gdr at ...> writes:
> >
> >>
> >> --On Wednesday, July 20, 2011 09:19:33 AM +0000 pskrap <pskrap at ...>
> >> wrote:
> >>
> >> > I have a cluster where some of the resources cannot run on the same node.
> >> > All  resources must be running to provide a functioning service. This
> >> > means that a  certain amount of nodes needs to be up before it makes
> >> > sense for the cluster to start any resources.
> >>
> >> Without knowing anything about your application, I would tend to question
> >> this statement.  Is it true that you must not start *any* resources before
> >> you have enough nodes, or is sufficient to say that the application
> >> is not considered up until all resources are started?  It may not
> >> make sense to run any, but does it do any harm?
> >>
> >> If you *can* start at least some resources before all nodes are available,
> >> then I would expect that you could get by with defining colocation
> >> constraints to ensure that some resources don't run on the same nodes,
> >> perhaps augmenting things with some order constraints if necessary.
> >>
> >> If your applications die or do other horrible stuff when only some subset
> >> are running then I'd have a talk with your application developers
> >> as it sounds like a larger robustness problem.
> >>
> >> Devin
> >>
> >
> > No, there are no crash issues etc when all resources are not running. The
> > application is just not usable until all resources are started.
> >
> > As for the harm, the resources which have constraints preventing them from
> > running will fail,
> 
> Are you talking about constraints in the pacemaker config or some other kind?

I was talking about pacemaker config constraints.

I found that by manually updating the expected-quorum-votes property to the 
number of nodes I want to install I can prevent pacemaker from reaching quorum 
early. It does not seem to update this property until the number of nodes 
reaches its number. Using this slight hack, pacemaker wont try to start 
anything until I have installed enough nodes. 

Another solution which may be better is to just to simply set the property stop-
all-resources=true until the last machine is installed and then set it to 
false, causing everything to start.