# Elasticsearch appears to be unreachable or down

**URL:** <https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751>\
**Category:** Elasticsearch\
**Created:** [October 29, 2020, 9:34pm UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751 "2020-10-29T21:34:07Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rgovinda](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rgovinda/32/75643_2.png) [@rgovinda](https://discuss.elastic.co/u/rgovinda)\
**Post date:** [October 29, 2020, 9:34pm UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751/1 "2020-10-29T21:34:07Z")

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We suddenly started seeing a huge increase ( from single digits to hundreds) in the error  
"Attempted to send a bulk request to elasticsearch' but Elasticsearch appears to be unreachable or down!}"  
This is causing significant drop (80%) in the amount of data making it to elastic cluster (8 data nodes and 3 master).  
we are running 7.4 logstash and elastic  
logstash pulls from kafka and pushes to elastic  
about 50 logstash instances  
any help will be appreciated

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**Author:** ![rugenl](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rugenl/32/12887_2.png) [@rugenl](https://discuss.elastic.co/u/rugenl)\
**Post date:** [October 30, 2020, 1:46am UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751/2 "2020-10-30T01:46:12Z")

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Check your heap usage and GC rates, when those go bad, it can happen quick.

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**Author:** ![rgovinda](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rgovinda/32/75643_2.png) [@rgovinda](https://discuss.elastic.co/u/rgovinda)\
**Post date:** [October 31, 2020, 4:05am UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751/3 "2020-10-31T04:05:24Z")

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thanks for the response. What are ideal values for GC count and duration rate? JVM heap is between max of 22.1 and min of 4.7. Mostly staying around 10 GB. GC duration is ~33ms with young at 0.5 avg

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**Author:** ![rugenl](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rugenl/32/12887_2.png) [@rugenl](https://discuss.elastic.co/u/rugenl)\
**Post date:** [October 31, 2020, 1:44pm UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751/4 "2020-10-31T13:44:41Z")

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Compare to before the problem, watch for percent of time in GC.

What is IO wait?

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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:** [November 28, 2020, 1:44pm UTC](https://discuss.elastic.co/t/elasticsearch-appears-to-be-unreachable-or-down/253751/5 "2020-11-28T13:44:44Z")

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