On Thu, Mar 8, 2018 at 2:38 AM, Ivan Kelly <iv...@apache.org> wrote: > > Given that RackAwareEnsemble policy defaults to finding a replacement > > bookie within > > the same rack, when a bookie is lost in a rack, the entire cluster will > be > > replicating > > to the same 'rack'. This puts a lot of pressure on the rack and also > takes > > a longer time > > to bring up the replication levels. > > I agree this has potential to be problematic. > > Perhaps we should provide a switch to RackAwareEnsemble, > 'preferReplaceInSameRack'. > > > I would think the right fix is to bring back the targetBookie concept > (with > > a configuration parameter) and add placement check predicate on top of > it. > > When this is configured > > each bookie picks up the work, checks if the ensemble placement policy > > gets satisfied, > > if so replicate it, if not move on. > > I don't think adding a predicate argument (I guess a > BiPredicate<Set<BookieSocketAddress>, BookieSocketAddress>?) to the > recover bookie call makes sense. There is already a way to customize > this behaviour, by passing in a EnsemblePlacementPolicy on > Configuration of the client. The behaviour you want can be achieved by > taking one of the current EnsemblePlacementPolicies and overriding > replaceBookie, though I guess that's not very user-friendly. However, > even if it was user-friendly, how would we make it easy for users to > supply a placementpolicy or a even a predicate, as you suggested, to > the autorecovery daemon. >
In the old model if the bookie is writable AND is not part of ensemble, replicate to the local(target) bookie. My proposal is t add anotehr AND condition. if bookie is writable AND not part of ensemble AND satisfies Enseble Placement Policy write to local(target) bookie. Thanks, JV > -Ivan > -- Jvrao --- First they ignore you, then they laugh at you, then they fight you, then you win. - Mahatma Gandhi
