At the moment I can't think of any reason why queries could not be served w/o ZK up and running.
Otis -- Solr & ElasticSearch Support -- http://sematext.com/ Solr Performance Monitoring -- http://sematext.com/spm On Mon, Sep 16, 2013 at 4:58 PM, Branham, Jeremy [HR] <jeremy.d.bran...@sprint.com> wrote: > I may be interpreting this incorrectly, but shouldn't the cloud still serve > requests if ZK crashes? > > http://wiki.apache.org/solr/SolrCloud#Example_C:_Two_shard_cluster_with_shard_replicas_and_zookeeper_ensemble > > " The problem with example B is that while there are enough Solr servers to > survive any one of them crashing, there is only one zookeeper server that > contains the state of the cluster. If that zookeeper server crashes, > distributed queries will still work since the solr servers remember the state > of the cluster last reported by zookeeper. The problem is that no new servers > or clients will be able to discover the cluster state, and no changes to the > cluster state will be possible." > > > > > > Jeremy D. Branham > Performance Technologist II > Sprint University Performance Support > Fort Worth, TX | Tel: **DOTNET > Office: +1 (972) 405-2970 | Mobile: +1 (817) 791-1627 > http://JeremyBranham.Wordpress.com > http://www.linkedin.com/in/jeremybranham > > > -----Original Message----- > From: Shawn Heisey [mailto:s...@elyograg.org] > Sent: Friday, September 13, 2013 2:40 PM > To: solr-user@lucene.apache.org > Subject: Re: Best configuration for 2 servers > > On 9/13/2013 12:50 PM, Branham, Jeremy [HR] wrote: >> Does this sound appropriate then? [assuming no 3rd server] >> >> Server A: >> Zoo Keeper >> SOLR with 1 shard >> >> Server B: >> SOLR with ZK Host parameter set to Server A > > Yes, that will work, but if the ZK on server A goes down, the entire cloud is > down. > > When you create a collection with replicationFactor=2, one replica will be on > server A and one replica will be on server B. > > If you want to break the index up into multiple shards, you can, you'll also > need the maxShardsPerNode parameter when you create the collection, and all > shards will have replicas on both machines. > > A note about zookeeper and redundancy, and an explanation about why 3 hosts > are required: To form a quorum, zookeeper must have the votes of a majority > of the hosts in the ensemble. If there are only two hosts, it's not possible > for there to be a majority unless both hosts are up, so two hosts is actually > worse than one. You need to either have one ZK node or at least three, > preferably an odd number. > > Thanks, > Shawn > > > > ________________________________ > > This e-mail may contain Sprint proprietary information intended for the sole > use of the recipient(s). Any use by others is prohibited. If you are not the > intended recipient, please contact the sender and delete all copies of the > message. >
