[sheepdog] [PATCH 0/9] allow new nodes joining before all old sheep are up

[Christoph Hellwig]

On Wed, Jun 13, 2012 at 10:42:03AM +0800, Liu Yuan wrote:
> On 06/12/2012 11:09 PM, Christoph Hellwig wrote:
> > This series allows to start new sheep when the cluster is in WAIT_FOR_JOIN
> > status.  They still don't count towards the number of required old sheep,
> > but will join the cluster as soon as old sheep have been seen.
> > 
> 
> I am not against the patch set per se (it does many more cleanups than
> the title advertise), but I just wonder is there any real use case for
> adding new sheep when we are recovering the crashed cluster?

The prime use case is to speed up recovering a cluster in that case.
Right now it requires manual intervention, which usually means some
sort of periodic restart.  Handling it correctly from the start not
only generally makes this case faster, it also simplifies the management
layer a bit.