On Thu, Sep 18, 2014 at 7:45 AM, Flavio Percoco <fla...@redhat.com> wrote: > On 09/18/2014 04:09 PM, Gordon Sim wrote: >> On 09/18/2014 12:31 PM, Flavio Percoco wrote: >>> Zaqar guarantees FIFO. To be more precise, it does that relying on the >>> storage backend ability to do so as well. Depending on the storage used, >>> guaranteeing FIFO may have some performance penalties. >> >> Would it be accurate to say that at present Zaqar does not use >> distributed queues, but holds all queue data in a storage mechanism of >> some form which may internally distribute that data among servers but >> provides Zaqar with a consistent data model of some form? > > I think this is accurate. The queue's distribution depends on the > storage ability to do so and deployers will be able to choose what > storage works best for them based on this as well. I'm not sure how > useful this separation is from a user perspective but I do see the > relevance when it comes to implementation details and deployments.
Guaranteeing FIFO and not using a distributed queue architecture *above* the storage backend are both scale-limiting design choices. That Zaqar's scalability depends on the storage back end is not a desirable thing in a cloud-scale messaging system in my opinion, because this will prevent use at scales which can not be accommodated by a single storage back end. And based on my experience consulting for companies whose needs grew beyond the capabilities of a single storage backend, moving to application-aware sharding required a significant amount of rearchitecture in most cases. -Devananda _______________________________________________ OpenStack-dev mailing list OpenStackemail@example.com http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev