I have some ideas about Swift multi-cluster organisation. Please give feedback on
https://lists.launchpad.net/openstack/msg08518.html On Sat, Mar 10, 2012 at 5:58 PM, John Leach <j...@brightbox.co.uk> wrote: > Hi, > > I'm looking at deploying swift across two data-centres - I'd like to > write 3 replicas: two in one data-centre and the third in the other > another (doesn't matter which way around). I'd like to be able to > tolerate the failure of (or loss of connectivity to) either data centre. > > If I create one zone per data-centre, I can't write 3 replicas (as each > replica needs to go in a different zone). > > I can create two zones per data-centre, which appears at first to do the > job, but I can't add any more zones to either data centre (without > increasing the replica count to ensure at least one copy is always in > the other data-centre). So if I lose access to one data-centre, and lose > one zone in the remaining data-centre, I can no longer make writes to > the required minimum 2 zones. > > I could use container replication here of course, but then I'll be > writing 6 replicas in all. > > 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). > > Apache Cassandra can do this kind of thing with it's RackAwareStrategy > replication strategy. You define which servers are in which racks and > which racks are in which data-centres. > > 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? > > Thanks! > > John. > -- > Brightbox UK Cloud - http://brightbox.com > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp > -- Kind regards Dmitry Ukov IT Engineer Mirantis, Inc.
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