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On Mar 10, 2012, at 5:58 AM, John Leach wrote:
> 
> I think what I need here is hierarchical zones - I'd define one parent
> zone per data-centre, and then multiple child zones within each
> (representing racks or whatever).
> 
> Swift would be configured to write 3 replicas in 3 child zones, aiming
> for at least 1 one replica per parent zone (handing off if the parent
> zone is unavailable).

This would be a great feature for swift, and it's very much in line with some things we've brainstormed about.

> 
> I saw an oscon 2011 swift talk slide that mentioned "layered zones" as
> future dev work - mentioning "cabinets, not zones".  Extrapolating from
> these 5 words, this is exactly what I need, when will it be ready? ;)
> 
> Any thoughts on this?  Can the existing Ring implementation be extended
> to do this kind of thing? Is the code modular enough to be able to make
> the Ring implementation pluggable?

Beyond gholt's brimring (which you looked at earlier), I don't know of any work that has been done on this. I certainly think that the existing ring can be modified to handle these use cases, but it's not really "pluggable" (beyond a replacement that supports the same methods). I'd like to see the existing ring implementation expanded for these use cases (and remain compatible with existing deployments) rather than move to a plugin/extensions/whatever model.

If you and others would like to work on these features, I think a large part of the swift community would gratefully accept it.

--John


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