[sheepdog-users] Split Brain Detection?

[Arnold Krille]

On Monday 18 June 2012 15:37:25 Bastian Scholz wrote:
> I have a small setup with only two host, each with one
> gateway and three worker sheeps. Today, I migrated all
> virtual machines to one of the host and shut down the
> other host (defect hardware).
> 
> But with one host down, sheepdog cluster stops working,
> because only the half of all sheeps where reachable and
> a (I guess) Split Brain Detection stops the other sheeps
> too.
> 
> On the one hand its a good behavior against split-brain
> situation, on the other hand, a very small cluster stops
> working completely...

This is most probably not a problem of sheepdog but has to do with corosync. 
Normal corosync needs quorum to run, that is more then half of the nodes need 
to be up. On a two-node cluster this leads to the effect you see.
Either add a third node or configure corosync to ignore the quorum. (But don't 
add a third node _and_ ignore quorum, that opens a can of worms named split-
brain.)

Have fun,

Arnold
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