# Elasticsearch as a primary store
**URL:** https://discuss.elastic.co/t/elasticsearch-as-a-primary-store/132647
**Category:** Elasticsearch
**Created:** [May 21, 2018, 11:26am UTC](https://discuss.elastic.co/t/elasticsearch-as-a-primary-store/132647 "2018-05-21T11:26:10Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Juris\_Rats](https://discuss.elastic.co/u/Juris_Rats)
#### Post date: [May 21, 2018, 11:26am UTC](https://discuss.elastic.co/t/elasticsearch-as-a-primary-store/132647/1 "2018-05-21T11:26:10Z")
Hi,
I have read a number of posts on the issue still not have answers to my questions.
I want to use ES in a scenario where:
- new and updateable data is replicated to ES indexes from the SQL database (when changes occur)
- old, read only data is stored in ES indexes only
I understand that ES may loose data (in some rare cases). I would like to set up some safe framework to handle those rare cases to be sure the data is not lost.
Questions I have are:
- are there any other use cases appart from the unavailability/crashing of cluster nodes, when the data may be lost? Can data be lost if all cluster nodes are available and working normally?
- is there a method I can safely detect each node unavailability/crash? Is every crash/unavailability logged?
- can data be lost for a read-only index? E.g. - while moved from one node to another because of loosing updates to cluster status?
Will be gratefull for any help
I use latest version of ES (6.2)
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [June 18, 2018, 11:26am UTC](https://discuss.elastic.co/t/elasticsearch-as-a-primary-store/132647/2 "2018-06-18T11:26:13Z")
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