# JVM -Xmx recommendations on search only nodes vs. data only nodes

**URL:** <https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409>\
**Category:** Elasticsearch\
**Created:** [May 27, 2015, 4:35pm UTC](https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409 "2015-05-27T16:35:29Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Chris\_Neal](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chris_neal/32/3527_2.png) [@Chris\_Neal](https://discuss.elastic.co/u/Chris_Neal)\
**Post date:** [May 27, 2015, 4:35pm UTC](https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409/1 "2015-05-27T16:35:29Z")

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Hello everyone,

I'm considering splitting my ES cluster into search-only nodes and data-only nodes. For data-only nodes, I will keep the -Xmx to \<= 32GB, and \<= half the machine's RAM (64GB).

I'm wondering though if those recommendations apply to search only nodes as well, or can I use more than 1/2 the machines RAM for ES JVMs because of the role of the node?

I would like to make the most of the RAM on the search nodes, and was considering running two ES JVMs with 24GB RAM each on a box with 64GB total, but wasn't sure if that was ok.

Can someone comment on that please?  
Thanks for your time!  
Chris

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**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [May 28, 2015, 9:10am UTC](https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409/2 "2015-05-28T09:10:00Z")

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For search/client and master nodes you can definitely increase the heap to more than 50%, after all they hold no data other than the cluster state so you don't need to worry about FS caching.

Running two instances sounds like a good idea, but contention could be a killer. Best to test to see how your hosts handle it.

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**Author:** ![Chris\_Neal](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chris_neal/32/3527_2.png) [@Chris\_Neal](https://discuss.elastic.co/u/Chris_Neal)\
**Post date:** [May 28, 2015, 2:46pm UTC](https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409/3 "2015-05-28T14:46:38Z")

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Thanks so much Mark.

That's what I was thinking, but appreciate the validation!

With regards to contention, I will test for sure and see if/where any contention points are found. It'll take me a bit to set it up, but I'll post back with my results in hopes that it might help others.

Thanks again for you help.  
Chris

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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, 12:11am UTC](https://discuss.elastic.co/t/jvm-xmx-recommendations-on-search-only-nodes-vs-data-only-nodes/1409/4 "2017-07-06T00:11:15Z")

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