# The purpose of coordinating\_only role

**URL:** <https://forum.opensearch.org/t/the-purpose-of-coordinating-only-role/23413>\
**Category:** OpenSearch\
**Tags:** configure\
**Created:** [February 14, 2025, 6:23am UTC](https://forum.opensearch.org/t/the-purpose-of-coordinating-only-role/23413 "2025-02-14T06:23:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![huckebein79](https://avatars.discourse-cdn.com/v4/letter/h/df705f/32.png) [@huckebein79](https://forum.opensearch.org/u/huckebein79)\
**Post date:** [February 14, 2025, 6:23am UTC](https://forum.opensearch.org/t/the-purpose-of-coordinating-only-role/23413/1 "2025-02-14T06:23:40Z")

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**Versions** (relevant - OpenSearch/Dashboard/Server OS/Browser): OpenSearch

**Describe the issue** :

Hi, I am testing OpenSearch configuration.

I know that I should config the roles of node as blank list for building coordinating node.

By the way, I found that there is “coorinating\_only” role in OpenSearch.  
When I config “coordinating\_only” role in OpenSearch node, It works as same as blank role.

Then, I wonder why “coordinating\_only” role exists in OpenSearch although we can create coordinating role with blank role.

Thanks in advance

**Configuration** :

**Relevant Logs or Screenshots** :

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**Author:** ![nateynate](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.opensearch.org/nateynate/32/4913_2.png) [@nateynate](https://forum.opensearch.org/u/nateynate)\
**Post date:** [February 19, 2025, 11:03pm UTC](https://forum.opensearch.org/t/the-purpose-of-coordinating-only-role/23413/2 "2025-02-19T23:03:42Z")

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> [@huckebein79](#):
>
> Then, I wonder why “coordinating\_only” role exists in OpenSearch although we can create coordinating role with blank role.

This would be a perfect issue and/or comment in the github repo for the core opensearch component. The developers are usually able to justify their decision making with great precision.

If I were to wager a guess, I would say it would be to prevent accidental replication and segmentation in case a node gets brought up on accident. If a node were to get brought up as a data node and start acting as a replica and/or start hosting segments of an index, it may not be intended and might even degrade the performance of a cluster. Setting the default role to coordinating only might be a safety measure.

Just a guess though. It’s a perfect question to put into an `issue` for the [OpenSearch Core Repo on Github](https://github.com/opensearch-project/OpenSearch)

And welcome back! I know your last post was several months ago.

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**Author:** ![pablo](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.opensearch.org/pablo/32/10363_2.png) [@pablo](https://forum.opensearch.org/u/pablo)\
**Post date:** [March 11, 2025, 9:27am UTC](https://forum.opensearch.org/t/the-purpose-of-coordinating-only-role/23413/3 "2025-03-11T09:27:01Z")

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@huckebein79 Please have a look at this GitHub commit. It explains the existence of the coordinating\_only role.

> <https://github.com/opensearch-project/OpenSearch/commit/106bed90c76207b8c748cc5902f099edc827b710>
>
> Today we can execute cluster API actions on only master, data or ingest nodes
> u…sing the \`master:true\`, \`data:true\` and \`ingest:true\` filters, but it is not
> so easy to select coordinating-only nodes (i.e. those nodes that are neither
> master nor data nor ingest nodes). This change fixes this by adding support for
> a \`coordinating\_only\` filter such that \`coordinating\_only:true\` adds all
> coordinating-only nodes to the set of selected nodes, and 
> \`coordinating\_only:false\` deletes them.
> 
> Resolves #28831.