# Ideal heap size for large RAM machine
**URL:** https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915
**Category:** Elasticsearch
**Created:** [December 15, 2017, 7:28am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915 "2017-12-15T07:28:29Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@vivek7mehta](https://discuss.elastic.co/u/vivek7mehta)
#### Post date: [December 15, 2017, 7:28am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915/1 "2017-12-15T07:28:29Z")
As suggested here:
[https://www.elastic.co/guide/en/elasticsearch/guide/current/heap-sizing.html](https://www.elastic.co/guide/en/elasticsearch/guide/current/heap-sizing.html)
I should give leas than half of my memory to Lucene. It also suggests that I says that I should not assign more than 32GB to elasticsearch JVM heap size.
My query is that I have machine with larger memory (200-300 GB). Is there any way I could use my spare memory to improve elasticsearch performance.
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [December 15, 2017, 7:37am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915/2 "2017-12-15T07:37:13Z")
If heap pressure and GC is having an impact on your performance, deploying more than one node with a heap just under 32GB on such a host can help. If your performance bottleneck on the other hand is e.g. disk I/O, that may however not necessarily help a lot.
Have you determined what is limiting performance in your setup?
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### Author:  [@vivek7mehta](https://discuss.elastic.co/u/vivek7mehta)
#### Post date: [December 15, 2017, 7:43am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915/3 "2017-12-15T07:43:59Z")
I am not sure exactly what is causing the issue, but Elasticsearch node is taking more time during startup (after startup it works normally). So I was wondering if increasing initial/maximum JVM heap size will have impact on that.
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [December 15, 2017, 7:45am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915/4 "2017-12-15T07:45:19Z")
Can you provide the full output of the [cluster stats API](https://www.elastic.co/guide/en/elasticsearch/reference/6.1/cluster-stats.html)?
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [January 12, 2018, 7:45am UTC](https://discuss.elastic.co/t/ideal-heap-size-for-large-ram-machine/111915/5 "2018-01-12T07:45:27Z")
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