# ElasticSearch and Split Brain? **URL:** \ **Category:** Elasticsearch\ **Created:** [June 19, 2012, 9:12pm UTC](https://discuss.elastic.co/t/elasticsearch-and-split-brain/8159 "2012-06-19T21:12:53Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![otisg](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/otisg/32/492_2.png) [@otisg](https://discuss.elastic.co/u/otisg)\ **Post date:** [June 19, 2012, 9:12pm UTC](https://discuss.elastic.co/t/elasticsearch-and-split-brain/8159/1 "2012-06-19T21:12:53Z")
Hello, How exactly does ElasticSearch handle Split Brain scenarios? I've asked this question on the Solr ML the other day and this is the finding: [http://search-lucene.com/m/3L3ht1xuETB1](http://search-lucene.com/m/3L3ht1xuETB1) The summary is, I think, as follows: 1. the cluster partition with insufficient number of ZooKeepers (less than what the quorum is), the partition will not accept adds/updates/deletes 2. the cluster partition with enough ZooKeepers to form the quorum will continue to take updates IFF it has at least one copy of each shard from the original cluster I think searches will be served by 2), but not 1) and there is now an issue open in Solr's JIRA to have 1) return search results, too, but with a flag indicating that results may not be complete or could be stale. How exactly does ES handle cluster partitioning? I've asked a concrete Q about how Rivers are handled in Split Brain situation and it looks like they are/were not handled well, meaning that each partition of the cluster would end up with its copy of the River, which I assume means there could be duplicate in the index once things are fixed and cluster partitions are united in a single cluster: [https://groups.google.com/d/msg/elasticsearch/5ndIc0qokDw/QdoJvHkO004J](https://groups.google.com/d/msg/elasticsearch/5ndIc0qokDw/QdoJvHkO004J) ## Thanks, Otis Search Analytics - [http://sematext.com/search-analytics/index.html](http://sematext.com/search-analytics/index.html) Scalable Performance Monitoring - [http://sematext.com/spm/index.html](http://sematext.com/spm/index.html) ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [June 21, 2012, 7:42am UTC](https://discuss.elastic.co/t/elasticsearch-and-split-brain/8159/2 "2012-06-21T07:42:34Z")
In terms of configuring a quorum, you can set the discovery.minimum\_master\_nodes setting. On Tue, Jun 19, 2012 at 11:12 PM, Otis Gospodnetic \< [otis.gospodnetic@gmail.com](mailto:otis.gospodnetic@gmail.com)\> wrote: > Hello, > > How exactly does Elasticsearch handle Split Brain scenarios? > I've asked this question on the Solr ML the other day and this is the > finding: [http://search-lucene.com/m/3L3ht1xuETB1](http://search-lucene.com/m/3L3ht1xuETB1) > > The summary is, I think, as follows: > > 1. the cluster partition with insufficient number of ZooKeepers (less than > what the quorum is), the partition will not accept adds/updates/deletes > 2. the cluster partition with enough ZooKeepers to form the quorum will > continue to take updates IFF it has at least one copy of each shard from > the original cluster > > I think searches will be served by 2), but not 1) and there is now an > issue open in Solr's JIRA to have 1) return search results, too, but with a > flag indicating that results may not be complete or could be stale. > > How exactly does ES handle cluster partitioning? > > I've asked a concrete Q about how Rivers are handled in Split Brain > situation and it looks like they are/were not handled well, meaning that > each partition of the cluster would end up with its copy of the River, > which I assume means there could be duplicate in the index once things are > fixed and cluster partitions are united in a single cluster: > [https://groups.google.com/d/msg/elasticsearch/5ndIc0qokDw/QdoJvHkO004J](https://groups.google.com/d/msg/elasticsearch/5ndIc0qokDw/QdoJvHkO004J) > > ## Thanks, Otis > > Search Analytics - [Cloud Monitoring Tools & Services | Sematext](http://sematext.com/search-analytics/index.html) > Scalable Performance Monitoring - [Sematext Monitoring | Infrastructure Monitoring Service](http://sematext.com/spm/index.html) ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:23am UTC](https://discuss.elastic.co/t/elasticsearch-and-split-brain/8159/3 "2017-07-06T03:23:09Z")
Closed on July 6, 2017, 3:23am UTC