# Occasional problems joining the cluster

**URL:** <https://discuss.elastic.co/t/occasional-problems-joining-the-cluster/9391>\
**Category:** Elasticsearch\
**Created:** [October 17, 2012, 1:29pm UTC](https://discuss.elastic.co/t/occasional-problems-joining-the-cluster/9391 "2012-10-17T13:29:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Michael\_Smolyak](https://avatars.discourse-cdn.com/v4/letter/m/7cd45c/32.png) [@Michael\_Smolyak](https://discuss.elastic.co/u/Michael_Smolyak)\
**Post date:** [October 17, 2012, 1:29pm UTC](https://discuss.elastic.co/t/occasional-problems-joining-the-cluster/9391/1 "2012-10-17T13:29:53Z")

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I am using ElasticSearch with my Grails application. When testing a  
clustered configuration of the app, I noticed that occasionally the two ES  
servers will not form a cluster but will be listed as two standalone  
server. I am using a multicast configuration on both server with the  
default group and custom port. Both instances are embedded with Grails app  
and run in "dataNode" mode. Most of the times the two server connect to a  
cluster (you can see through ElasticSearch Head the configuration of the  
cluster). Sometimes, however, ES Head will show the two server as running  
two separate instances. No error messages are visible on the console. What  
may casue such erratic behavior? How to prevent it?

Thank you,

Michael

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**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, 3:08am UTC](https://discuss.elastic.co/t/occasional-problems-joining-the-cluster/9391/2 "2017-07-06T03:08:18Z")

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Closed on July 6, 2017, 3:08am UTC