I'm not sure what the expected behavior is. However, as of 7.4.0, it doesn't seem like there is any attempt to prevent both the new leader and follower replicas from being created on the same instance.
Sometimes for one of the sub-shards, the new leader and one of the new followers end up on the same instance. We just manually end up moving them since we don't split shards very often. Best, Chris On Wed, Jan 30, 2019 at 12:46 PM Rahul Goswami <rahul196...@gmail.com> wrote: > Hello, > I have a followup question on SPLITSHARD behavior. I understand that after > a split, the leader replicas of the sub shards would reside on the same > node as the leader of the parent. However, is there an expected behavior > for the follower replicas of the sub shards as to where they will be > created post split? > > Regards, > Rahul > > > > On Wed, Jan 30, 2019 at 1:18 AM Rahul Goswami <rahul196...@gmail.com> > wrote: > > > Thanks for the reply Jan. I have been referring to documentation for > > SPLISHARD on 7.2.1 > > < > https://lucene.apache.org/solr/guide/7_2/collections-api.html#splitshard> > which > > seems to be missing some important information present in 7.6 > > < > https://lucene.apache.org/solr/guide/7_6/collections-api.html#splitshard>. > > Especially these two pieces of information.: > > "When using splitMethod=rewrite (default) you must ensure that the node > > running the leader of the parent shard has enough free disk space i.e., > > more than twice the index size, for the split to succeed " > > > > "The first replicas of resulting sub-shards will always be placed on the > > shard leader node" > > > > The idea of having an entire shard (both the replicas of it) present on > > the same node did come across as an unexpected behavior at the beginning. > > Anyway, I guess I am going to have to take care of the rebalancing with > > MOVEREPLICA following a SPLITSHARD. > > > > Thanks for the clarification. > > > > > > On Mon, Jan 28, 2019 at 3:40 AM Jan Høydahl <jan....@cominvent.com> > wrote: > > > >> This is normal. Please read > >> > https://lucene.apache.org/solr/guide/7_6/collections-api.html#splitshard > >> PS: Images won't make it to the list, but don't think you need a > >> screenshot here, what you describe is the default behaviour. > >> > >> -- > >> Jan Høydahl, search solution architect > >> Cominvent AS - www.cominvent.com > >> > >> > 28. jan. 2019 kl. 09:05 skrev Rahul Goswami <rahul196...@gmail.com>: > >> > > >> > Hello, > >> > I am using Solr 7.2.1. I created a two node example collection on the > >> same machine. Two shards with two replicas each. I then called > SPLITSHARD > >> on shard2 and expected the split shards to have one replica on each > node. > >> However I see that for shard2_1, both replicas reside on the same node. > Is > >> this a valid behavior? Unless I am missing something, this could be > >> potentially fatal. > >> > > >> > Here's the query and the cluster state post split: > >> > > >> > http://localhost:8983/solr/admin/collections?action=SPLITSHARD&collection=gettingstarted&shard=shard2&waitForFinalState=true > >> < > >> > http://localhost:8983/solr/admin/collections?action=SPLITSHARD&collection=gettingstarted&shard=shard2&waitForFinalState=true > > > >> > >> > > >> > > >> > > >> > Thanks, > >> > Rahul > >> > >> >
