On Tuesday 28 October 2014 10:42:11 Bernd Fehling wrote: > Thanks for the explanations. > > My idea about 4 zookeepers is a result of having the same software > (java, zookeeper, solr, ...) installed on all 4 servers. > But yes, I don't need to start a zookeeper on the 4th server. > > 3 other machines outside the cloud for ZK seams a bit oversized. > And you have another point of failure with the network between ZK and cloud. > If one of the cloud servers end up in smoke the ZK system should > still work with ZK and cloud on the same servers. > > So the offline argument says the first thing I start is ZK and > the last I shutdown is ZK. Good point. > > While moving fom master-slave to cloud I'm aware of the fact that > all shards have to be connected to ZK. But how can I tell ZK that > on server_1 is leader shard_1 AND replica shard_4 ?
You don't, it will elect a leader by itself. > > Unfortunately the "Getting Started with SolrCloud" is a bit short on this. > > > Regards > Bernd > > Am 28.10.2014 um 09:15 schrieb Daniel Collins: > > As Michael says, you really want an odd number of zookeepers in order to > > meet the quorum requirements (which based on your comments you seem to be > > aware of). There is nothing "wrong" with 4 ZKs as such, just that it > > doesn't buy you anything above having 3, so its one more that might go > > wrong and cause you problems. In your case, I would suggest you just pick > > the first 3 machines to run ZK or even have 3 other machines "outside" the > > cloud to house ZK. > > > > The offline argument is also a good one, you really want your ZK instances > > to be longer lived than Solr, whilst you can restart individual Cores > > within a Solr Instance, it is often (at least for us) more convenient to > > bounce the whole java instance. In that scenario (again just re-iterating > > what Michael said), you don't want ZK to be down at the same time. > > > > If you are using Solr Cloud, then all your replicas need to be connected > > to > > ZK, you can't have the master instances in ZK, and the replicas not > > connected (that's more of the old Master-Slave replication system which is > > still available but orthogonal to Cloud). > > > > > > On 28 October 2014 07:01, Bernd Fehling <bernd.fehl...@uni-bielefeld.de> > > > > wrote: > >> Yes, garbage collection is a very good argument to have external > >> zookeepers. I haven't thought about that. > >> But does this also mean seperate server for each zookeeper or > >> can they live side by side with solr on the same server? > >> > >> > >> What is the problem with 4 zookeepers beside that I have no real > >> gain against 3 zookeepers (only 1 can fail)? > >> > >> > >> Regards > >> Bernd > >> > >> Am 27.10.2014 um 15:41 schrieb Michael Della Bitta: > >>> You want external zookeepers. Partially because you don't want your > >>> Solr garbage collections holding up zookeeper availability, > >>> but also because you don't want your zookeepers going offline if > >>> you have to restart Solr for some reason. > >>> > >>> Also, you want 3 or 5 zookeeepers, not 4 or 8. > >>> > >>> On 10/27/14 10:35, Bernd Fehling wrote: > >>>> While starting now with SolrCloud I tried to understand the sense > >>>> of external zookeeper. > >>>> > >>>> Let's assume I want to split 1 huge collection accross 4 server. > >>>> My straight forward idea is to setup a cloud with 4 shards (one > >>>> on each server) and also have a replication of the shard on another > >>>> server. > >>>> server_1: shard_1, shard_replication_4 > >>>> server_2: shard_2, shard_replication_1 > >>>> server_3: shard_3, shard_replication_2 > >>>> server_4: shard_4, shard_replication_3 > >>>> > >>>> In this configuration I always have all 4 shards available if > >>>> one server fails. > >>>> > >>>> But now to zookeeper. I would start the internal zookeeper for > >>>> all shards including replicas. Does this make sense? > >>>> > >>>> > >>>> Or I only start the internal zookeeper for shard 1 to 4 but not > >>>> the replicas. Should be good enough, one server can fail, or not? > >>>> > >>>> > >>>> Or I follow the recommendations and install on all 4 server > >>>> an external seperate zookeeper, but what is the advantage against > >>>> having the internal zookeeper on each server? > >>>> > >>>> > >>>> I really don't get it at this point. Can anyone help me here? > >>>> > >>>> Regards > >>>> Bernd
